LEARNING SEQUENCE 3

TEACHER GUIDE

THE GLOBE PROGRAM

Storms on the Move

Heating Up

Air Movement in the Tropics

A Curveball

ENGAGE

EXPLORE

EXPLAIN

ELABORATE

TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

| TEACHER GUIDE

Worldwide Weather

Why do storms move in predictable patterns

around the world?

The purpose of this learning sequence is for students to gure out why storms move the way they do,

on a global scale. While the weather can change day-to-day, the investigative phenomenon anchoring

this learning sequence is that prevailing winds at dierent latitudes move moisture in predictable pat-

terns. Students investigate how solar radiation leads to uneven heating of the atmosphere. Students

leverage existing Model Ideas from Learning Sequence 1 and new ideas about solar radiation to ex-

plain how this uneven heating causes convection on a global scale. They develop a model to explain

air movement in the tropics and test their models to see if they can explain precipitation movement

patterns near the equator. Students realize their current models only explain the north to south

movement of winds. They read and develop understandings about how the Coriolis eect causes

winds to curve, accounting for the east to west movement near the equator. Students can then pre-

dict the directions storms would travel in various locations around the world. This sequence shifts the

spatial scales and focus, as students move from examining what causes storms to form over several

days across a region to explaining why storms move in predictable patterns around the world.

Concentrated sunlight heats the Earth more at the equator than at the poles. This causes warm,

moist air to rise near the equator, creating areas of low pressure that lead to clouds and rainfall,

releasing water vapor and cooling the air. This air cools more as it is forced away from the equator,

sinks at 30˚N and 30˚S and is pulled toward the low pressure area at the equator to replace the ris-

ing air. This is convection on a global scale. The Earth’s rotation creates three areas of circulation in

each hemisphere. In the tropics, winds move across Earth’s surface toward the equator—prevailing

winds known as the trade winds. The Earth’s rotation causes prevailing winds to curve due to the

Coriolis eect. In the tropics, prevailing winds move from east to west. In the midlatitudes, they

move from west to east, leading to predictable patterns of storm movement around the world.

GLOBE Weather | LS3: Worldwide Weather

100

| TEACHER GUIDE

Background Science Content

THE SUN’S ENERGY AND LATITUDE

The Sun’s energy heats the Earth’s surface unevenly. Latitudes at or near

the equator are warmer overall than places that are far from the equator

(towards the North and South Poles), which receive less sunlight per unit of

area. This is because the Sun is most directly overhead and most intense near

the equator and lower in the sky at higher latitudes where the same amount

of energy is spread out over a larger area. As you listen to student ideas

about why it is warmer near the equator, note that some students might

think that temperatures are warmer near the equator because those places

are “closer to Sun,” and temperatures are cooler in the midlatitudes because

those places are “farther from the equator and therefore farther from the

Sun.”

Additionally, locations far from the equator have strong seasonal dierences

in temperature, and locations at or near the equator have little or no

seasonal dierences in temperature (aside from that caused by storms or

other weather phenomena). This occurs because Earth’s axis is tilted, so a

location far from the equator receives more sunlight at times of year when its

hemisphere is tilted towards the Sun and less sunlight at times of year when

its hemisphere is tilted away from the Sun.

These variations with latitude are explored in Lesson 13, in which students interpret data that shows general dierences in

temperature between Earth’s poles and the equator.

GLOBAL ATMOSPHERIC CIRCULATION

While weather can change day-to-day, surface winds at dierent latitudes move in predictable ways. These surface winds are

part of a pattern of global atmospheric circulation, which is the result of the Sun heating the Earth more at

the equator than at the poles (because there are dierences in air temperature around the Earth,

the air circulates). In places where warm air is rising, air pressure is low. In places where cool

air is sinking, air pressure is high. The systematic rising of warm air and sinking of cool

air is called convection and describes the circulation of air in predictable patterns,

or circulation cells, around the Earth. There are three circulation cells in each

hemisphere: the Hadley cell, Ferrel cell, and polar cell as shown in the image.

The Hadley cells are located between the equator and 30° north and

south of the equator. At the equator, warm, moist air rises, creating

areas of low pressure that leads to clouds and rainfall, releasing water

vapor as air rises to the top of the troposphere (the tropopause). The

air, now cooler, is forced north and south of the equator, and it cools

even more. At 30° north and south of the equator, the cooler, drier

air sinks towards the ground creating high pressure. Some of the

sinking air travelsto higher latitudes,forming the Ferrel cell,and rises

at about 60° north and southlatitude. Some of that rising air moves

towards the poles then sinks as part of the polar cell.

High pressure areas are found at 30° north and south. These latitudes

have stable weather (warm/dry). Many deserts are located near 30° north

and south where high pressure areas are located. Low pressure areas are

located at the equator and at 50°-60° north and south and have unstable

weather (more clouds and precipitation). In the midlatitudes and at the equator,

there is more precipitation especially along the west coast of continents associated

with low pressure areas.

Equator

30 ºN

60 ºN

Low angle of incoming sunlight

Sunlight directly overhead

Incoming sunlight at various latitudes

(Credit: SA Geography)

equator

North

Pole

South

Pole

Hadley cell

Ferrel cell

polar cell

Ferrel cell

GLOBE Weather | LS3: Worldwide Weather

101

| TEACHER GUIDE

THE CORIOLIS EFFECT

Global atmospheric circulation is also aected by the spin of the Earth. The Earth spins from west to east on its axis. Because

the Earth is widest at the equator, it rotates faster at the equator than at the poles, and surface winds (or objects) are

deected, or turned, by the Coriolis eect.

The Coriolis eect is zero at the equator and then increases in magnitude towards the poles. The Coriolis eect is the apparent

acceleration of a moving body as a result of the Earth’s rotation (deecting the direction of the north-south air). If the Earth

didn’t spin, there would be just one large convection cell between the equator and poles. The deecting winds split the one cell

into three convection cells.

• The NOAA SciJinks website (https://scijinks.gov/coriolis/) provides an explanation about the Coriolis eect that may

be helpful for students.

The Coriolis eect greatly impacts the prevailing wind direction on a global scale (see image below).

The prevailing winds at the Earth’s surface, caused by convection, are deected by Earth’s rotation, causing them to curve to

the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The (surface) trade winds in the tropics are

associated with the Hadley cells and move towards the equator, southwest in the Northern Hemisphere and northwest in the

Southern Hemisphere. In the midlatitudes, where the Ferrel cells are located, warmer surface air moving poleward is deected

east by the Coriolis eect, which leads to prevailing westerly surface winds (west to east) in both hemispheres. At the higher

latitudes, where the polar cells are located, the prevailing surface winds are easterly (east to west) in both hemispheres.

In addition, on a smaller scale, air moving toward an area of low pressure and away from high pressure is also inuenced by

the Coriolis eect. Air moves counterclockwise around low pressure in the Northern Hemisphere and clockwise around low

pressure in the Southern Hemisphere. This is why storms in the Northern Hemisphere rotate counterclockwise, while storms

in the Southern Hemisphere rotate clockwise.

60° N

30° N

30° S

60° S

0°

Intertropical

convergence

zone

Polar cell

Mid-latitude cell

Hadley cell

Mid-latitude cell

Polar cell

Westerlies

HIGH

Northeasterly Trades

Southeasterly Trades

Westerlies

Credit: Kaidor

creativecommons.org/licenses/by-sa/3.0

GLOBE Weather | LS3: Worldwide Weather

102

| TEACHER GUIDE

It is warmer at the equator be-

cause it is closer to the Sun.

While it is true that the Earth “bulges” at the equator, there is no signi-

cant dierence in the distance to the Sun, whether measuring from the

equator or from the poles. The reasoning for warmer temperatures at

the equator is because of the angle of the Sun; at the equator the Sun

is directly overhead, providing more heat, while areas further from the

equator receive less direct sunlight and thus less heat.

For more information, visit:

https://serc.carleton.edu/sp/library/guided_discovery/examples/sea-

sons.html

Summer occurs when the Earth

is closest to the Sun and winter

when the Earth is farthest from

the Sun.

Similar to the reasoning in the misconception above, it is not the dis-

tance between the Sun and the Earth that causes the extreme changes

in latitudinal and seasonal temperatures (In fact, the Earth is closest

to the Sun in January, which is winter for the Northern Hemisphere,

and farthest from the Sun in July, when the Northern Hemisphere is

experiencing summer). The reason for the seasons is the 23.5° tilt of

the Earth on its axis, which means that each hemisphere experiences

warm seasons when it is pointed more directly at the Sun and cold

seasons when it is pointed away from the Sun.

For more information, visit:

https://spaceplace.nasa.gov/seasons/en/

Heat from the Earth’s core is

responsible for heat at the Earth’s

surface.

While it is true that the Earth’s core and mantle are extremely hot

(the source of this heat is the decaying of radioactive elements within

the Earth as well as residual heat from when the Earth formed), as

students discovered in Learning Sequence 1, Earth’s surface tempera-

ture is a result of incoming radiation from the Sun. The amount of heat

energy owing to the surface from the Earth’s interior is only about

1/10,000

of the amount of energy ow from the Sun to the Earth’s

surface.

For more information, visit:

https://www.skepticalscience.com/heatow.html

COMMON MISCONCEPTIONS:

The following science misconceptions were identied by GLOBE Weather eld test teachers. Watch out for them as your

students are learning about weather.

MISCONCEPTION CORRECT EXPLANATION

103

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

STORMS ON THE MOVE

How do storms move around the world?

AT A GLANCE

ACTIVITY DESCRIPTION MATERIALS

(50 minutes)

Global Precipitation Patterns

Students watch a video and record observations of precip-

itation movement patterns rst in North America and then

globally. They share observed patterns and generate ques-

tions in small groups, followed by a whole class discussion.

Students add new questions to the Driving Question Board.

Lesson 12: Student Activity Sheet

North America storm movement time-lapse

video

NASA rainfall and snowfall video

Whiteboard, smart board, or chart paper

and markers (to make the Driving Question

Board)

Develop Initial Explanations

Students develop initial ideas to explain these patterns in

global precipitation movement, drawing on prior experi-

ence and Model Ideas from Learning Sequences 1 and 2.

GLOBE Weather | LS3: Worldwide Weather

104

| TEACHER GUIDE

NGSS Sensemaking

Students observe patterns of storm movement across North America and around the world

to identify the phenomenon anchoring Learning Sequence 3: there are predictable patterns of

precipitation movement around the world, and patterns are dierent in the tropics and midlatitudes.

Students generate questions about what is causing these patterns. Students develop initial

explanations, drawing on their understanding about how temperature and pressure cause water

vapor movement from Learning Sequences 1 and 2.

PERFORMANCE OUTCOME

• Make observations to describe the large-scale motion of water in the atmosphere.

• Describe patterns of how water moves through the atmosphere around the world.

NGSS DIMENSIONS (GRADES 6-8)

• Ask questions that arise from careful observation of phenomena to seek additional

information.

• Develop a model to describe unobservable mechanisms.

• Apply scientic ideas to construct an explanation for real-world phenomena.

• Images can be used to identify patterns in data.

• The complex patterns of the changes and the movement of water in the atmosphere are

major determinants of local weather patterns.

STORMS ON THE MOVE

How do storms move around the world?

105

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Teacher Procedures

Global Precipitation Patterns

1. Navigate from the previous lesson. At the end of the previous lesson, students followed one

storm moving across the United States. Help the class think about how that is a very long way

for moisture to travel.

Pose the questions:

• Where do you think the storm was a day before? Where was it two days before?

• Where do you think the moisture for that storm came from?

Tell students that in this activity they are going to investigate the global pattern of storm move-

ment.

Note: Prior experience with world maps and the global view of Earth will allow the remaining

activities to go more smoothly. Introduce world maps, a globe, and/or Google Earth if needed.

2. Observe storm movement patterns across North America. Tell students that one way to

identify regular patterns in storm movement is to look at weather patterns from a satellite

point of view from above instead of from locations on the ground. Introduce students to

the North America Storm Movement video context (see below). Tell students they will make

observations from the video:

• While students watch the video for the rst time, have them make observations without

taking notes. Point out a cold front over the central U.S. to connect with what students

learned in Learning Sequence 2.

• Watch the video a second time, and now have students take notes and draw the path

of the storms on their student activity sheets (Lesson 12: Step 1). Focus students on

monitoring the direction that storms travel.

STORMS ON THE MOVE: How do storms move around the world?

Storyline Link

Continuing a discussion

of storm movement is a

critical link to maintain

coherence as students

move from Learning

Sequence 2 to Learning

Sequence 3.

Patterns in Data

Students identify patterns

in storm movement across

North America.

NORTH AMERICA STORM MOVEMENT TIME-LAPSE VIDEO

Time-lapse video of storm movement across North America from

March to April 2017

https://www.youtube.com/watch?v=jC3H2k8lONU&feature=youtu.be

In this video, the white areas are places with more water vapor (moisture) in the air, which

indicates where precipitation is happening. The date appears in the upper left. Students are

seeing the curvature of Earth in this video because the satellite is so far away, so due east is

in the upper right and due west is in the upper left.

Two cold fronts pass though this video:

• The best option is March 6–8

• A second option is March 29–31

If students would like to see if the same pattern is visible at another time of year, have them

watch the time-lapse video from January to February:

https://www.youtube.com/watch?v=ntC070Sh9t0&feature=youtu.be

STEP 1

106

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Storyline Link

The patterns in the NASA

global rainfall and snowfall

video are the phenomena

anchoring Learning

Sequence 3. Students will

return to these patterns

several times.

STORMS ON THE MOVE: How do storms move around the world?

3. Discuss observations as a class. Draw out ideas around the west to east pattern across North

America. Patterns students might notice are as follows:

• Air with water vapor in it generally travels west to east across North America.

• Air with water vapor in it travels in squiggly, curling, and/or spinning lines.

• Certain areas have repeated patterns in cloud cover (e.g., the West Coast gets a lot

of water vapor from the Pacic Ocean, and some areas, like Mexico, have a “pulsing

pattern” in water vapor).

4. Have students think about why it’s important to understand why storms move

in predictable patterns. In Lesson 12: Step 2, have students record ideas about why

understanding storm movement patterns might be helpful to people and their communities.

Have students share some of these ideas.

5. Consider how air moves around the world. Ask students if they think there are similar

patterns in other parts of the world and prepare them to look for that in the next video.

6. Observe precipitation movement patterns around the world. Introduce students to the

NASA rainfall and snowfall video context (see below). Tell students they will make observations

from the video. Play the video and mute the sound.

• The rst time students watch the video, have them make visual observations without

taking notes. Discuss their initial observations of storm movement patterns across North

America.

• Watch the video a second time, now taking notes and drawing on the map in Lesson 12:

Step 3. You may want to show the video multiple times or pause the video to allow for

note taking.

SUGGESTED PROMPTS SAMPLE STUDENT RESPONSES

How could understanding patterns of

storm movement be helpful to people

and communities?

For people, it’s helpful to prepare for rain (e.g.,

like knowing what to wear).

For communities, it’s helpful to know when an

event is going to happen (e.g., so that people

can prepare and stay safe).

Patterns in Data

Students identify patterns

in storm movement

globally.

NASA GLOBAL RAINFALL AND SNOWFALL VIDEO

Satellite measurements of global precipitation from April to

September 2014.

https://pmm.nasa.gov/education/videos/gpms-rst-global-rainfall-

and-snowfall-map

This two-minute video shows how precipitation moves globally from April to September

2014, with data collected just below the clouds. The green-yellow-red colors indicate rainfall

and the blue-purple colors indicate snowfall, which students may not notice in the video. The

voiceover explains how the data was collected and some patterns students might notice,

so we suggest muting. The video provides a global view and zooms in on the United States

(0:25), South America (0:50), and the Atlantic Ocean (1:25).

STEP 3

STEP 2

107

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

7. Share observations and generate questions in small groups. Have students discuss their

observations and generate questions about those observations in small groups or pairs.

Question prompts for discussion are in Lesson 12: Step 4.

• What patterns do you notice about how precipitation moves around the world?

• What questions do you have about those patterns?

8. Conduct a whole class discussion. Discuss the guiding question: “How does precipitation move

around the world in predictable patterns?” Draw out students’ ideas working toward the following

key patterns:

KEY PATTERN: Precipitation near the equator moves from east to west.

KEY PATTERN: Precipitation in the midlatitudes moves from west to east.

9. Generate questions to investigate in Learning Sequence 3. Have students share their

questions about the observed patterns. Add these questions to the Driving Question Board

to reference throughout the learning sequence. Focus students on causal questions and elicit

responses to the following key questions:

• Why do storms move in predictable patterns around the world?

• Why do storms in the tropics move in dierent directions than the midlatitudes?

• Why do storms move from east to west near the equator in the Northern Hemisphere?

• Why do storms move from west to east in the midlatitudes in the Northern Hemisphere?

Develop Initial Explanations

1. Navigate from the previous lesson. Tell students that they’ll try to answer the following

questions in Learning Sequence 3:

• Why do storms move in predictable patterns around the world?

• Why do storms move in dierent directions in the tropics and midlatitudes?

2. Form initial ideas about causes of precipitation movement patterns, based on what we

already know. Have students answer the questions in Lesson 12: Step 5 of their student activity

sheets to begin to explain what could be causing the patterns of storm movement. Pull out the

Model Idea Tracker and encourage them to use what they learned from Learning Sequences 1

and 2. As students work, circulate and prompt students who are stuck:

• What do you already know about what causes rain?

• What do you already know about what causes air to move?

• What would cause storms to move?

• How could the same processes aect the whole world?

Model Ideas that might help students:

• Hot air rises as part of convection (Learning Sequence 1).

• Cool air sinks as part of convection (Learning Sequence 1).

• Air moves from areas of high to low pressure (Learning Sequence 2).

STORMS ON THE MOVE: How do storms move around the world?

STEP 4

STEP 5

Storyline Link

These questions set the

stage for what students

will investigate in Learning

Sequence 3.

Storyline Link

These questions guide

student investigations in

Learning Sequence 3.

Cause-Effect

Students start thinking

about what could be

causing precipitation

movement patterns.

Asking Questions

Students generate

questions based on

observed patterns of

worldwide precipitation

movement.

108

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

3. Facilitate a whole class discussion about students’ initial explanations. Have students

share their initial explanations (answers to Lesson 12: Step 5: Question 3). Consider recording

multiple and conicting student ideas in a public place to be revised later (e.g., chart paper,

PowerPoint, smart board). If students have conicting ideas, pull out the important Model Ideas

they are drawing on.

4. Look forward to the next lesson. Allow multiple explanations to linger. Tell students

that there are a few things to investigate. In the next lesson, they’ll start by investigating

temperature:

• How might temperature cause air to move on a global scale?

STORMS ON THE MOVE: How do storms move around the world?

Developing Explanations

Students develop initial

explanations for the

observed patterns.

GLOBE Weather | LS3: Worldwide Weather

109

| TEACHER GUIDE

AT A GLANCE

HEATING UP

Why is it hotter at the equator than other places on Earth?

ACTIVITY DESCRIPTION MATERIALS

(90 minutes)

Latitudinal Patterns of Temperature

Have students revisit the patterns of moving air (Lesson 12)

and think about how heat may be involved. Students explore

patterns in average annual temperatures worldwide and no-

tice that heat is concentrated at the equator. This leads to the

question: Why is it hotter at the equator than other locations

around the world?

Lesson 13: Student Activity Sheet

Global map of average annual temperatures

scied.ucar.edu/sites/default/les/images/ba-

sic-page/annual_mean_temperature_graph-

ic_ls3.jpg

Energy Angles

Students investigate dierent angles of light to think about

how the surface of Earth is curved, causing incoming solar

radiation to hit more directly at the equator and spread out

toward the poles.

Inatable globe

Clipboard

Flashlight

Ruler

Graph paper

Colored pencils

Temperature Data Investigation

Using GLOBE temperature data for ve locations at dierent

latitudes, students use what they have learned about uneven

heating at dierent latitudes to explain the patterns in the

ve locations.

GLOBE Temperature and Latitude Data card

sets (see pages 128-132 of this Learning

Sequence)

Model Idea Tracker

Students revisit their Model Ideas about uneven heating pat-

terns on Earth and revisit the lesson question: “Why does air

move in dierent ways around Earth?” They think about how

uneven heating might help them answer part of this question.

Whiteboard, smart board, or chart paper and

markers (to make the Model Idea Tracker)

GLOBE Weather | LS3: Worldwide Weather

110

| TEACHER GUIDE

NGSS Sensemaking

Students identify patterns in average annual temperatures worldwide and gure out the equatorial

region is much warmer consistently throughout the year and the midlatitudes have, on average,

generally cooler temperatures (although there is seasonal variation). Students then conduct an

investigation using a model to explore the causal mechanisms for these temperature dierences by

latitude and gure out that they are caused by uneven heating of a spherical earth. Students apply

this new understanding to explain patterns in temperature in ve cities around the world. They will

also use this knowledge to help explain global convection in Lesson 14.

PERFORMANCE OUTCOME

• Analyze a model to describe latitudinal variations in the concentration of sunlight and to

explain variations in temperature.

• Analyze data to describe global patterns in average annual temperatures.

NGSS DIMENSIONS (GRADES 6-8)

• Use a model to generate data to test ideas about phenomena in natural systems, including

those at unobservable scales.

• Analyze and interpret graphical displays of data to identify relationships.

• Construct an explanation using models or representations.

• Construct a scientic explanation based on valid and reliable evidence obtained from

students’ own experiments.

• Graphs, charts, and images can be used to identify patterns in data.

• Weather and climate are inuenced by interactions involving sunlight. These interactions

vary with latitude.

HEATING UP

Why is it hotter at the equator than other places on Earth?

111

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Teacher Procedures

Latitudinal Patterns of Temperature

1. Navigate from the previous lesson. At the end of the previous lesson, students discussed

what they noticed about the movement of weather in North America and globally. Remind

students that they have been thinking about how heating can cause air to move and that

heating can also cause pressure dierences.

The question they are trying to answer now is:

• How might temperature cause air to move in dierent ways on a global scale?

2. Ask students: “What are some ideas we have about how temperature aects air

movement?” Encourage students to use models and rules of thumb from Learning Sequences

1 and 2 as well as prior knowledge that might help them explain why air would move. Track

student thinking on the board. Students will likely say something about hot or cold air (based

on what they learned in Learning Sequence 1). Use this idea to link to the next step.

3. Show students a global map of average annual temperatures (Lesson 13: Step 1). Ask

students to study the map and write down patterns they notice. Then, as a whole class, ask

students to share the temperature patterns they noticed. Most students will notice that it is

much warmer at the equator than the poles, and there is a gradient between. They may also

point out the parallel pattern between the northern and southern hemispheres.

• KEY PATTERN: Temperatures are warmer at the equator and cooler at the poles.

• KEY PATTERN: Temperature follows a pattern of warmer bands in the middle (and

around the equator) and cooler bands toward the poles.

4. Ask students: “Why is it hotter at the equator than other places on Earth?” Give students

time to think about this and write down some initial ideas below the map in Lesson 13: Step

1 of their activity sheets. Ask students to share their thinking with the class. (Note: Students

might say, “The equator is hotter because it’s closer to the Sun.” This is a common student

misconception, which should be cleared up by the Energy Angles activity below. If students

have this misconception, make sure to address it directly after the Energy Angles activity.)

Tell students that in the next activity, they will use a model to explore why it’s hottest at the

equator.

Energy Angles

Set up the Energy Angles activity. Tell students: “We are going to use a ashlight, clipboard,

and graph paper to study what happens when sunlight strikes Earth’s surface.” Prior to starting,

ask students to explain what the following parts of the set-up represent:

• What does the ashlight represent? [Sunlight]

• What does the clipboard represent? [The Earth’s surface]

STEP 1

Storyline Link

Revisit the question posed

at the end of Lesson 12 to

remind students of the

focus of this lesson.

Developing & Using

Models

Students use a model to

think about how the Sun’s

incoming energy affects

temperatures on Earth.

Patterns in Data

Students identify patterns

in annual average global

temperatures.

Going Deeper

Try this additional

activity to help students

understand the relative

size of Earth and the Sun

and the distance between

them:

sunearthday.nasa.

gov/2007

/materials/solar_pizza.pdf

HEATING UP: Why is it hotter at the equator than other places on Earth?

112

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Data Analysis &

Interpretation

Students analyze and

interpret data from their

graph paper to think about

where solar radiation is

more concentrated and

more spread out on Earth.

Going Deeper

To collect more data, you

can tilt a small photovoltaic

cell that is connected to a

small motor or voltmeter.

Have students measure the

amount of tilt and record

the amount of energy.

2. Give students about 10 minutes to complete the activity. Use Lesson 13: Step 2 in the

student activity sheet.

HEATING UP: Why is it hotter at the equator than other places on Earth?

STEP 2

NOTES:

• This activity works best in groups of three: one student to hold the clipboard (the

surface of the Earth), one student to hold the ashlight and ruler (the Sun), and one

student to trace where the light falls on the graph paper (the recorder).

• If possible, darken your classroom or move to a room without windows.

• Students will shine their ashlights down on the paper from straight above while

the clipboard is lying at on the table and

again when the clipboard is tilted at an

angle (with one edge resting on the table).

When creating the angled set-up, tilt the

clipboard to about 45˚ or more.

• Both times the recorder will outline the

area that the ashlight lights up. Consider

having students use dierent colors and

overlap the images (e.g., shine the light in

approximately the same spot both times) to

accentuate the dierences.

• The distance between the ashlight and

the paper will vary depending on how

bright your ashlight is. Students will want

to choose a distance that allows the entire image

to t on the paper with ample space around the

borders. The investigation works best when the

ashlight is fairly close to the paper, at a distance

of less than 5 cm.

• It is important that the distance between the

ashlight and the clipboard stay the same the

whole time, but also equally important that the

ashlight remain pointing straight down towards

the table, even when the clipboard is titled at an

angle. If it helps, point out to students that the

Sun is not changing position, but rather we are

changing where we are on the Earth; when the

Earth’s surface is at we are at the equator, and

when the Earth’s surface is tilted we have moved

far from the equator. Use a globe to point out

hypothetical locations on the Earth where we

might be “standing.”

**To do this activity as a demonstration instead, shine a ﬂashlight straight above

onto the ceiling of a darkened room and then angled at the ceiling.**

STRAIGHT ON

TILTED

113

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

3. Make sense of the data. As a whole class, ask students to share their ndings from the

investigation. Ask students: “When did the light cover more of the paper, straight on or tilted?”

Consider asking if any of the groups counted the number of squares illuminated, and if so,

which way lighted more squares. Students will notice that there were more squares lit when

the clipboard was tilted.

Use the following questions to guide a discussion to make sense of what this means:

• Was there any dierence in the amount of light coming from the ashlight? Did it change or

stay the same?” [The amount did not change.]

• So what happened when you tilted the clipboard? [The area got bigger; the light spread

out.]

• If you were standing in one of the squares on the clipboard, within which one do you think

you would feel the most heat? Why? [Help students realize that it would be hotter in the

circle where the heat is more concentrated and cooler in the circle where the heat is

more spread out.]

Now, let’s think about what this means for Earth. Demonstrate shining the ashlight

directly at the equator of the inatable globe, holding the ashlight horizontally. Then, keeping

the ashlight horizontal, shine the light toward the poles. If students need support relating

their clipboard model to the Earth, have a student hold their clipboard at the equator (so that

it is vertical) and then at a high latitude location (so that it’s at an angle). Have them make

connections between where the light is more concentrated (the smaller circle on the graph

paper) and where the light is more spread out. (Alternatively, project the “What does this mean

for Earth’s surface?” slide with the image of the Earth instead of using the physical model.)

4. Have students apply these ideas to diagrams of what this means for uneven heating on

Earth. Say: “We are going to use what we just did with the ashlights and clipboards to think

about what this would look like on Earth’s surface.” Direct them to Lesson 13: Step 3. Ask, “What

do you notice about this image?” Students should notice that the “clipboard” from Lesson 13:

Step 2 is now placed at certain points on Earth (e.g., the slanted clipboard could be the Earth’s

surface at midlatitudes and the non-slanted clipboard could be the Earth’s surface at the

equator). Students should think about where solar radiation is more concentrated and where it

is more spread out (less concentrated) as they answer the questions.

5. What did this activity help us gure out related to our question: Why is it hotter at the

equator than other places on Earth? Ask students to summarize what they learned from the

Energy Angles activity.

Write these ideas on the Model Idea Tracker.

• Sunlight (solar radiation) is more concentrated at the equator because incoming sunlight

shines directly on the equator, concentrating it in a smaller area.

• Sunlight (solar radiation) is more spread out toward the poles because incoming sunlight

hits the surface at an angle, spreading the light out over a larger area.

• The amount of concentrated solar radiation that warms the land inuences air

temperatures just above the land. More concentrated solar radiation causes higher air

temperatures. More spread out solar radiation causes cooler air temperatures.

Note: This is where you can end the lesson for the rst day.

HEATING UP: Why is it hotter at the equator than other places on Earth?

STEP 3

Storyline Link

Revisit where students are

in Lesson 13 if this lesson

is taught across multiple

class periods.

114

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Temperature Data Investigation

1. Tell students they are going to look closer at temperature data by latitude. If you split

this lesson across two days of class time, begin day two by asking students to describe general

dierences in temperature between Earth’s poles and the equator and why they believe there

are dierent temperatures. Revisit the Model Idea Tracker as needed to remind students where

they are in the investigation of uneven heating between the equator and the poles.

2. Divide students into groups and preview the GLOBE Temperature and Latitude data

graph cards, location cards, and maximum/minimum temperature cards to orient

students to the activity. Pass out a card set to each group. Ask students what they notice

about the graphs. Students may notice the following:

• The x-axis is time and this data was collected over several years.

• The data in dierent places was not collected over the same time period.

• Some graphs have strong shifts in temperature over seasons, and some locations have

little variation.

Tell students that GLOBE students in ve locations around the world took measurements

of maximum daily temperature (the warmest temperature each day) and that these are the

graphs of that data. Their task is to gure out the location of the data based on what they

understand about how temperatures vary by latitude. (Note: The graphs introduce seasonal

shifts in temperature, which is NOT part of this unit. If you have already taught seasons in your

class, this is a good place to have students make connections. If you have not taught seasons in

your class, ask students to focus on the range of temperatures, focusing on where warmer and

cooler temperatures are and not the seasonal shifts within the year.)

GLOBE Locations:

• Juuan Lukio/Poikolan Koulu, Finland

• WANAKA Field Station, Vermont, USA

• Many Farms High School, Arizona, USA

• Hamzah Bin Abdulmutalib Secondary School at Jeddah, Saudi Arabia

• Wp/Minu/D S Senanayake College, Sri Lanka

3. Allow students time to match the graphs/temps/locations for each of the ve locations.

Have the groups share their initial matches with another group and discuss any dierences

before they begin to record them on the student activity sheet.

4. In Lesson 13: Step 4, have students complete

their explanations of locations based on the

temperature and latitude data. Using the clues

below, students can revisit their matches and

then write down their nal best guesses.

CLUE 1: Seasonal dierences (uctuations from

cold to warmer temperatures) are stronger at

higher latitude (further from the equator). At or

near the equator, there is usually no seasonal

dierence in temperature.

CLUE 2: Temperatures are warmer at low latitude (close to the equator) than at high latitude

(far from the equator).

STEP 4

HEATING UP: Why is it hotter at the equator than other places on Earth?

Data Analysis &

Interpretation

Students analyze and

interpret temperature data

and latitude for ve GLOBE

locations.

CORRECT MATCHES

Location Graph High/Low

Finland B I

Vermont E J

Arizona A H

Saudi Arabia C F

Sri Lanka D G

115

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Model Idea Tracker

1. Revisit the Model Idea Tracker to summarize Model Ideas about uneven heating.

Summarize the Model Ideas from this lesson.

• Sunlight (solar radiation) is more concentrated at the equator because incoming sunlight

shines directly on the equator, concentrating it in a smaller area.

• Sunlight (solar radiation) is more spread out toward the poles because incoming sunlight

hits the surface at an angle, spreading the light out over a larger area.

• The amount of concentrated solar radiation inuences air temperatures; more

concentrated solar radiation causes higher air temperatures and more spread out solar

radiation causes cooler air temperatures.

Then ask students: “So we know that Earth is heated unevenly by the Sun. Some places have

more direct solar radiation; other places have more spread out solar radiation. That causes

temperature dierences on Earth. But how does that have anything to do with how air moves?”

Give students a few minutes to ponder this question. Ask if they can pull from the Model Idea

Tracker, particularly as it relates to pressure dierences and air temperatures. Some students

may say something about dierent air temperatures being related to convection. Push them

to explain how temperature dierence might cause convection. Build on this idea by telling

students that they will think about temperature dierences and how they cause air to move in

the next lesson.

Tell students: “We saw dierent patterns of storm movement in the tropics and the midlati-

tudes. Next time, we’ll start by thinking solely about the tropics and how uneven heating and air

movement relate in that region.”

• How does uneven heating relate to air movement in the tropics?

HEATING UP: Why is it hotter at the equator than other places on Earth?

GLOBE Weather | LS3: Worldwide Weather

116

| TEACHER GUIDE

ACTIVITY DESCRIPTION MATERIALS

(90 minutes)

Develop a Working Model

Students pull their ideas together from Learning Sequences

1, 2, and 3 to develop an initial model to explain how and

why air moves in the atmosphere in the tropics.

Lesson 14: Student Activity Sheet

Optional: NASA rainfall and snowfall video

Convection Demonstration

Students observe convection in a class demonstration.

Students gure out that winds move toward the equator

in global convection. Students then add these ideas to the

Model Idea Tracker.

Clear tub

Cold water

Red and blue food coloring

Two pipettes

Kettle and near boiling water

Five insulated cups

Optional: Device for time-lapse/

slow-motion video

Global Air Circulation Diagram

Students review a diagram of global air circulation and

record observations, initial explanations, and questions. In

a whole class discussion, students discuss how convection

happens on a global scale and add additional Model Ideas

to the Model Idea Tracker.

Whiteboard, smart board, or chart paper

and markers (to make the Model Idea

Tracker)

Consensus Model: Air Movement in the Tropics

Students use the Model Idea Tracker to develop a Consen-

sus Model for explaining how and why air moves in the

tropics. Students develop models in small groups and then

share their models with the class and come to consensus.

Whiteboard, smart board, or chart paper

and markers (to make the Consensus

Model)

AIR MOVEMENT IN THE TROPICS

How and why does air move in the tropics?

AT A GLANCE

GLOBE Weather | LS3: Worldwide Weather

117

| TEACHER GUIDE

NGSS Sensemaking

Students develop a model to explain how and why air moves in large-scale convection in the tropics.

Students develop an initial model drawing on understandings from Learning Sequences 1, 2, and

3. Students gather evidence about how air moves in global convection from critical review of a

diagram and a convection demonstration. Students revise models in small groups and develop a class

Consensus Model.

PERFORMANCE OUTCOME

• Develop a model to show how air is circulating through the atmosphere in the tropics and

midlatitudes.

NGSS DIMENSIONS (GRADES 6-8)

• Develop a model to describe unobservable mechanisms.

• Construct an explanation using models or representations.

• Weather and climate are inuenced by interactions involving sunlight and the atmosphere.

These interactions vary with latitude, which can aect atmospheric ow patterns.

AIR MOVEMENT IN THE TROPICS

How and why does air move in the tropics?

118

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Teacher Procedures

Develop a Working Model

1. Revisit the Learning Sequence 3 phenomenon and question: Why do storms move in

predictable patterns around the world? Remind students that the class is investigating how

air moves on a global scale because air movement is related to patterns in storm movement.

(Optional: Show the NASA global rainfall and snowfall video from Lesson 12 to remind students

of the precipitation movement pattern in the tropics.)

2. Navigate from the previous lesson. At the end of the previous lesson, students gured out

that solar radiation causes uneven heating of Earth, which leads to air temperature dierences.

Students gured out that air at the equator will be warmer than air in the midlatitudes. Remind

students of the next question to investigate:

• How does uneven heating relate to air movement in the tropics?

3. Prepare students to develop a Working Model. Tell students they will develop a Working

Model to explain how and why air moves in the tropics. Have students review the Model Idea

Tracker to draw on ideas from lessons 1 to 13. Tell students that not all ideas will be helpful, but

some might.

• Encourage students to draw on ideas from the previous lesson about solar radiation as

well as ideas from Learning Sequence 1 about how temperature relates to air movement

and ideas from Learning Sequence 2 about how pressure relates to air movement.

• Remind students that the purpose is for them to try to draw on their existing knowledge

to start developing an explanation. They don’t need to be certain about their models at

this point.

4. Orient students to the illustration of the Earth’s atmosphere in Lesson 14: Step 1 of the

student activity sheet. Show the cross section of Earth’s atmosphere (slide: Layers of the

Atmosphere) and relate it to the illustration on their activity sheets. While the atmosphere does

have four distinct layers, the illustration on their activity sheets is focusing just on the Earth’s

surface and the troposphere layer of the atmosphere, because this is where all weather occurs.

5. Students record an initial Working Model. In Lesson 14: Step 1 of their student activity sheets,

students record a model that explains how air movement in the tropics relates to latitude.

Encourage students to share their working models with others as they nish.

Use the following prompts to guide students as you circulate the class:

• Where might air be rising from Earth’s surface to the atmosphere and why?

• Where might air be sinking from the atmosphere to Earth’s surface and why?

STEP 1

Storyline Link

Students remember

that they’re exploring

air movement because

precipitation is moisture in

the air, and they are trying

to explain patterns in

global storm movement.

Developing & Using

Models

Students draw on Model

Ideas from Learning

Sequences 1, 2, and 3 to

develop a Working Model to

explain how air moves in

the tropics.

AIR MOVEMENT IN THE TROPICS: How and why does air move in the tropics?

119

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

AIR MOVEMENT IN THE TROPICS: How and why does air move in the tropics?

Convection Demonstration

1. Introduce the goal of the Convection Demonstration. Tell students that the goal of this

demonstration is to help them think about how and why air moves across the Earth’s surface in

global convection near the equator. Students can also make observations about the rest of the

convection cycle.

Storyline Link

In this activity, students

think about how air

would move across

Earth’s surface in global

convection, which would

cause patterns in storm

movement.

CONVECTION DEMONSTRATION

MATERIALS:

• Clear tub (about the size of a shoebox)

• Cold water (enough to ll the clear tub ¾ full)

• Red and blue food coloring

• Two pipettes

• Hot water

• Device to heat water (e.g., kettle)

• Five cups of the same height (four to hold up the tub and one for hot water)

PREPARATION:

• Fill the clear tub with cold water and place the tub on top of four cups. Let the

water settle. Place the tub in front of a light-colored background.

TO BE DONE WITH STUDENTS IN CLASS:

1. Heat water using a kettle and ll an insulated cup.

2. Use a pipette to carefully place a large drop of red food coloring at the bottom

of the center of the tub.

3. Use a pipette to carefully place two large drops of blue food coloring at the

bottom of each side of the tub.

4. Place the cup with hot water underneath the red drop of food coloring at the

center of the tub.

This video shows the set-up: https://scied.ucar.edu/convection-demonstration

BLUE

HOT

WATER

BLUERED

N 30

(equator)

120

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

2. Discuss what each part of the tank represents. Orient students to the demonstration set-up

and discuss what each part represents. Students can ll in the middle column (“Part of the real

world”) in Lesson 14: Step 2 as you discuss.

• The water in the tank represents air. This model uses water to simulate air because both

air and water are uids, so they behave similarly, but water can be seen.

• The red food coloring represents air at the equator.

• The blue food coloring represents air at 30°N and 30°S.

• The cup full of hot water represents solar radiation.

• The bottom of the tank represents Earth’s surface.

Have students work with a partner to ll out the third column (“Why are they alike?”) of the

analogy map in Lesson 14: Step 2. Students should come up with reasoning to explain why the

analogy works (e.g., Why is red coloring a good choice to represent air at the equator?).

3. Prepare for observations. Students may wish to make a video or take photos. They might

sketch or write about the changes. Explain that having several ways to document what is

happening is a good idea because dierent types of data can be used together to help us

understand what is happening. Have students plan how they will document what happens in

the tank.

4. Set-up the demonstration. Explain how the demonstration will be completed. The key idea

here is that students watch what is happening along the bottom of the tank, as it represents

air movement, or winds, across Earth’s surface. Ask students to predict what will happen when

the cup of hot water is added. Put the red and blue food coloring drops at the base of the tank.

Heat the water, add it to the cup, and place the cup with hot water under the red food coloring

in the tank. It will take about one minute for the red dye to start rising and convection to start.

The blue dots should also slowly begin to pull towards the center of the tank (towards the red

dot).

5. Make observations. Have students draw what they notice happening in the tank in Lesson

14: Step 3 of their activity sheets. Students should observe that the red food coloring rises and

the blue food coloring is pulled in from the sides of the tank to the middle of the tank. Have

students record their ideas about what they see, why they think it is happening, and what they

wonder about in the boxes below their drawings.

6. Relate the convection demonstration to how and why air moves in the tropics. Orient

students to the model, pointing out that we are focusing only on the convection cells near

the equator. Have students develop a model in Lesson 14: Step 4, using their observations of

the tank to describe how air is moving in the tropics (between 30°N and 30°S of the equator).

Students should be able to explain why air is rising and sinking.

7. Share observations and lead a discussion of the demonstration. Have students explain

what they observed and why it happened. Use the following questions to guide this discussion:

AIR MOVEMENT IN THE TROPICS: How and why does air move in the tropics?

STEP 2

STEP 3

STEP 4

121

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Disciplinary Core Idea

Students deepen their

conceptual understanding

about how temperature

and pressure causes air

movement in convection.

Students expand their

understanding that

convection also happens

on a global scale.

AIR MOVEMENT IN THE TROPICS: How and why does air move in the tropics?

SUGGESTED PROMPTS SAMPLE STUDENT RESPONSES

What happened to air at the surface

of the Earth when it received direct

heat?

The air near the equator heated up from the

Sun and rose.

What happened to the pressure where

the warm air rose?

The warm rising air caused an area of low

pressure.

Why would the air move from the cool

location to the warm location?

As the warm air rises, it creates an area of low

pressure. Cool air moved toward the area of low

pressure across the Earth. That’s the wind we

would feel.

Students may need support to understand why the cool air is pulled across Earth’s surface

toward the equator. This is a good time to remind students what they know about pressure

and how air moves from high to low pressure. Students may also not realize that this horizontal

movement represents winds. Have them think about what they would feel if they stood at the

bottom of the tank. Remind them that the bottom of the tank represents the Earth’s surface.

8. Revisit the Model Idea Tracker to summarize Model Ideas about air movement.

Summarize the new Model Ideas from this lesson and record them on the Model Idea Tracker.

Model Ideas:

• As warm air rises at the equator, it creates an area of low pressure.

• Cooler air with higher pressure moves across Earth’s surface toward the area of low

pressure to replace the rising warm air.

• Horizontal movement of air across Earth’s surface is wind.

Global Air Circulation Diagram

Note: Do not hand out Lesson 14: Step 5 until students get to this point, as the previous steps involve

students discovering the pattern of convection cells that is provided here.

1. Introduce the Global Air Circulation Diagram in Lesson 14: Step 5. Orient students to this

diagram and point out that it shows how air moves around the whole world, not just in the

tropics.

2. Have students create a model of air pressure and humidity. Annotating the illustration

in Lesson 14: Step 5, students should create a model locating the areas of low and high

atmospheric pressure and the locations that are likely to be cloudy because air is rising. Use

the arrows indicating air movement as clues.

3. Lead a class discussion about the diagram. Focus students on convection near the equator

and encourage students to draw on their understanding of convection from Learning Sequence

1 and high and low pressure from Learning Sequence 2 to explain air movement in tropical

convection. The one important thing for students to notice in the midlatitudes at this point is

that convection moves in the opposite direction. This will be revisited in Lesson 15. Use the

prompts below to guide your discussion.

STEP 5

122

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

4. Document new Model Ideas on the Model Idea Tracker at the end of the discussion.

Students ﬁgure out the following:

• Warm air is rising at the equator because of concentrated sunlight (solar radiation),

which heats air, causing it to rise. An area with rising air has low pressure.

• Cool air is sinking at 30°N and 30°S, which is an area of high pressure.

• Convection happens on a global scale.

5. Ask students what we would experience on the surface of the Earth. Have students

wonder about what the air movement would be like if we were standing at the surface of the

Earth near the equator. Tell students that air movement across Earth’s surface is what we

experience as wind. It’s okay if students are not sure about this yet.

• If you stood just north of the equator, where would you feel winds coming from?

• If you stood just south of the equator, where would you feel winds coming from?

Consensus Model: Air Movement in the Tropics

1. Revisit the Learning Sequence 3 phenomenon and question: Why do storms move in

predictable patterns around the world? Remind students that the class is investigating air

movement patterns because precipitation is moisture in the air. Remind students that we’re

focusing only on air movement in the tropics for now. Review the question that the Consensus

Model will help us answer:

• How and why does air move in the tropics?

SUGGESTED PROMPTS SAMPLE STUDENT RESPONSES

Where is air rising from Earth’s surface

into the atmosphere and why?

Warm air is rising at the equator because there

is more concentrated sunlight (solar radiation)

there. Warm air is also rising at the top of the

midlatitudes.

Worldwide, where is air sinking from

the atmosphere to Earth’s surface

and why?

Cool air is sinking at 30°N and 30°S. Cool air is

also sinking at the poles.

How is air moving across Earth’s

surface and why?

We’re not sure, but the arrows are pointing

toward the equator, so it looks like air is moving

toward the equator.

Where do you think there are areas of

high and low pressure and why?

We think there’s low pressure at the equator

where the warm air is rising, like the isolated

storm. There’s probably high pressure around

30°N and 30°S where cool air is sinking.

Assessment

Use this discussion to

formatively assess student

learning about global

convection.

Storyline Link

Students remember

that they’re exploring

air movement because

precipitation is moisture in

the air, and they are trying

to explain patterns in

global storm movement.

Developing & Using

Models

Use the Model Idea Tracker

to document new rules

students gured out

about air circulation in

the tropics. Remember

these are general rules of

thumb that will be helpful

for explaining global storm

movement patterns.

AIR MOVEMENT IN THE TROPICS: How and why does air move in the tropics?

123

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

2. Take stock of ideas from the Model Idea Tracker that will help answer this question.

Have students nominate ideas from the Model Idea Tracker that they think will be helpful for

answering this question. All of the ideas from Learning Sequence 3 will be helpful as well as

some ideas from Learning Sequences 1 and 2 about warm air rising, cool air sinking, and air

moving from high to low pressure.

3. Develop a class Consensus Model. Have small groups consider ideas from the models they

created in Lesson 14: Step 4 and Step 5 and the ideas from the Model Idea Tracker. Have each

group present which ideas they propose including in the Consensus Model. As small groups

present, have students discuss if they agree or disagree with the ideas in each groups’ model.

Come to consensus about what should be in the model and document a Consensus Model in a

public space that reects agreed upon ideas.

KEY MODEL IDEAS THAT SHOULD BE REPRESENTED IN THE CONSENSUS MODEL

• As warm air rises at the equator, it creates an area of low pressure.

• Sunlight (solar radiation) is more concentrated at the equator because incoming sunlight

shines directly on the equator, concentrating it in a smaller area.

• Sunlight (solar radiation) is more spread out toward the poles because incoming sunlight

hits the surface at an angle, spreading the light out over a larger area.

• The amount of concentrated solar radiation inuences air temperatures; more

concentrated solar radiation causes warmer air temperatures and more spread out solar

radiation causes cooler air temperatures.

• There are more areas where warm air is rising near the equator and more areas where

cool air is sinking at 30°N and 30°S.

• Cooler air moves along the surface of the Earth toward the area of low pressure to

replace the rising warm air.

• Horizontal movement of air along the surface of the Earth is wind, which causes storms

to move.

Developing & Using

Models

Students use ideas from

the Model Idea Tracker to

develop a class Consensus

Model to explain how

and why air moves in the

tropics. As students work

in groups, they do not need

to agree on all parts of the

model. They contribute

questions to the Consensus

Model discussion. Have the

Model Idea Tracker and

evidence from previous

activities ready to revisit

during the consensus

discussion to help resolve

disagreements.

Assessment

Students’ small group

models may serve as tools

for formative assessment.

AIR MOVEMENT IN THE TROPICS: How and why does air move in the tropics?

GLOBE Weather | LS3: Worldwide Weather

124

| TEACHER GUIDE

A CURVEBALL

When air and storms move, why do they curve?

ACTIVITY DESCRIPTION MATERIALS

(55 minutes)

Use the Consensus Model

Students use the Consensus Model to predict how air

moves across Earth’s surface in the tropics. Students re-

view observed storm movement patterns in the tropics and

realize that the model doesn’t explain why precipitation at

the equator moves from east to west.

Lesson 15: Student Activity Sheet

Coriolis Eect Reading

Students gather evidence from an article that explains the

Coriolis eect and how Earth’s rotation causes air to curve.

Students discuss the Coriolis eect in a whole class discus-

sion and add new ideas to the Model Idea Tracker.

Round balloons, markers

Explaining Storm Movement

Students use their global air circulation models and new

ideas about the Coriolis eect to explain where precipita-

tion would travel in the Philippines and where they live.

AT A GLANCE

GLOBE Weather | LS3: Worldwide Weather

125

| TEACHER GUIDE

NGSS Sensemaking

Students use the Consensus Model to explain precipitation movement patterns near the equator and

realize their model does not account fully for the phenomenon. Students critically read a scientic

text to gather information about how the rotation of Earth causes winds to curve, the Coriolis eect.

Students use their Consensus Model and new ideas about the Coriolis eect to explain patterns of

storm movement in two new locations.

PERFORMANCE OUTCOME

• Use knowledge of surface wind patterns to make a prediction about the movement of a

storm.

NGSS DIMENSIONS (GRADES 6-8)

• Use a model to predict phenomena.

• Evaluate limitations of a model for a proposed tool.

• Critically read scientic texts adapted for classroom use to obtain scientic information to

describe evidence about the natural world.

• Weather and climate are inuenced by interactions involving sunlight and the atmosphere.

These interactions vary with latitude, which can aect atmospheric ow patterns.

• Phenomena may have more than one cause.

NGSS DIMENSIONS (GRADES 3-5) (REINFORCING)

• Patterns of change can be used to make predictions.

A CURVEBALL

When air and storms move, why do they curve?

126

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Teacher Procedures

Use the Consensus Model

1. Navigate from the previous lesson. Remind students that they just developed a Consensus

Model to explain air movement in the tropics. Remind students of the Learning Sequence 3

question and how it connects to air movement.

• Why do storms move in predictable patterns around the world?

2. Use the model to predict how storms move in the tropics. Have students use their Air

Movement in the Tropics Consensus Model to predict how air or wind moves across Earth’s

surface in the tropics. Orient students to where storms would occur in their model (at the

bottom of the atmosphere). Students should deduce that, because of convection, storms would

move towards the equator in the tropics.

• Based on what you know about air movement in the tropics, predict storm movement in the

tropics.

3. Compare predictions to observed storm movement patterns. Re-watch the NASA global

rainfall and snowfall video from Lesson 12: Step 3 and focus students on storm movement

in the tropics. After watching the video, students record the answer to the question below in

Lesson 15: Step 1 of their student activity sheets. Students should notice very obvious patterns

of storms moving from east to west that our model doesn’t explain.

• What kind of movement do you see that isn’t explained by the model for air movement in the

tropics that you made at the end of Lesson 14?

4. Discuss the limitations of the model. Remind students that all models need to be revised

and tested and revised again. This model is not yet helping us fully explain observed patterns

of precipitation movement at the equator, nor is it addressing questions about precipitation

movement generated in Lesson 12 that are on the Driving Question Board:

• Why does precipitation move from east to west near the equator?

• Why does precipitation move from west to east in the midlatitudes?

• Why does precipitation move in dierent directions in the tropics and midlatitudes?

Storyline Link

Students review the

phenomenon and

remember that they’re

exploring air movement

because precipitation is

moisture in the air, and

they are trying to explain

patterns in global storm

movement.

A CURVEBALL: When air and storms move, why do they curve?

STEP 1

Developing & Using

Models

Students realize the

limitations of their model

and that their model does

not yet fully help them

explain the observed

phenomenon.

NASA GLOBAL RAINFALL AND SNOWFALL VIDEO

https://pmm.nasa.gov/education/videos/gpms-rst-global-rainfall-

and-snowfall-map

This two-minute video shows how precipitation moves globally from April to September

2014, with data collected just below the clouds. The green-yellow-red colors indicate rainfall

and the blue-purple colors indicate snowfall, which students may not notice in the video.

The voiceover explains how the data was collected and some patterns students might

notice, so we suggest muting. The video provides a global view and zooms in on the United

States (0:25), South America (0:50), and the Atlantic Ocean (1:25).

127

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

Coriolis Eect Reading

1. Navigate from the previous activity. Tell students that the model they developed explains

the north-south aspect of storm movement in the tropics but not the east-west movement.

2. Read the rst paragraph in Lesson 15: Step 2 about the Coriolis eect. Read this aloud with

your students to introduce the new idea that the spinning of the Earth deects winds.

3. Observe the Coriolis eect with a quick activity: Provide pairs of students with a round

balloon and marker. Instruct students to inate the balloon and draw an equator around the

widest point in the center of the balloon. Also draw on the balloon “about” where the 30˚N

latitude and 30˚S latitude lines would be. Tell students that this is a simple model of the Earth.

Have one student hold the balloon at chest height (they should be able to look down at the

top of the balloon) while the other draws an arrow starting at 30˚N going toward the equator.

Then have the student holding the balloon slowly rotate it counterclockwise (to model the Earth

spinning on its axis) as their partner draws another arrow, starting again from the same point

on their balloon. Students should notice that when their model of Earth was turning, the arrow

curved, but when their model wasn’t spinning, it did not.

4. Finish Reading about the Coriolis eect in Lesson 15: Step 2. Set the purpose of reading

an article as a method to help students gather evidence to explain the east-west storm

movement they observed in the video as well as additional evidence to explain the west-east

storm movement in the midlatitudes. Students can read individually or as a whole group.

Prompt students to Stop and Think as they encounter questions in the text. These questions

are to help students make connections between the information they read and their previous

observations.

5. Discuss the Coriolis eect. Lead a whole class discussion about the Coriolis eect. The big

ideas students should walk away with are that the winds do move north and south, caused by

convection, and they also move east and west, caused by the Earth’s rotation.

The unit thus far focused on explaining the north-south movement of air in tropical convection.

Students may struggle to see how air moves across Earth’s surface toward the poles in

midlatitude convection. You can help students see that convection in the midlatitudes travels in

the opposite direction.

Storyline Link

Students are motivated to

gather more evidence to

explain the phenomenon.

Literacy Connection

Students read non-ction

texts and are prompted to

make connections and to

synthesize ideas.

Going Deeper

Have students blow up a

balloon and use a marker

to draw an equator. Make

the knot the South Pole

and the top of the balloon

the North Pole. Have one

partner rotate the balloon

left to right, simulating

Earth’s rotation, while

the other partner slowly

tries to draw a straight

line from the North Pole

to the equator. Next, the

partner with the marker

will draw a straight line

from the South Pole to the

equator. Students see how

the movement “curves”

in opposite directions in

the northern and southern

hemispheres.

A CURVEBALL: When air and storms move, why do they curve?

SUGGESTED PROMPTS SAMPLE STUDENT RESPONSES

Why does the air in the tropics curve

east to west?

The Earth rotates so air that was moving toward

the equator curves and moves to the west.

How does air move across Earth’s

surface in midlatitude convection?

Air moves toward the poles. This is the opposite

direction as in the tropics.

Why does the air in the midlatitudes

move west to east?

The Earth rotates so air that was moving

towards the poles curves and moves to the east.

STEP 2

128

| TEACHER GUIDE

GLOBE Weather | LS3: Worldwide Weather

6. Add new ideas to the Model Idea Tracker. Summarize the new model ideas developed out of

this discussion and add them to the Model Idea Tracker.

Model Ideas

• In the tropics, air moves across Earth’s surface towards the equator due to convection.

• In the tropics, air moves across Earth’s surface east to west due to the Earth’s rotation.

• In the midlatitudes, air moves across Earth’s surface toward the poles due to convection.

• In the midlatitudes, air moves across Earth’s surface west to east due to the Earth’s

rotation.

Explaining Storm Movement

1. Navigate from the previous activity. Tell students that with their new ideas about the

Coriolis eect, they are now prepared to explain more of the patterns in storm movement they

observed in the tropics and the midlatitudes.

2. Record a nal explanation. In Lesson 15: Step 3, have students use their model and new ideas

about the Coriolis eect to record an explanation that describes where it is likely that storms

will originate in the Philippines and where they live.

3. Lead a whole class discussion. Have students share their explanations for where weather

comes from where they live and why this understanding is important for their daily lives. Have

them connect back to their responses from Lesson 12.

• Where is it likely that storms originate where we live?

• Why is being able to anticipate where storms come from important for communities?

• How can we use our understanding of weather to prepare for the impacts of storms?

4. Connect back to the Anchor. Have students look back at their Lesson 11 weather map

model. On a world map, globe, or Google Earth, indicate the location of Colorado. Ask students

to identify what direction storms are likely to travel based on its latitude. (Students should

recognize that it is in the midlatitudes so storms will tend to move from west to east.) Have

students add an arrow to their weather map models to indicate the direction that the storm is

trying to move. Ask students what stopped the storm from moving (high pressure to the east,

north, and south).

End of Sequence Assessment

Assess student learning with the Learning Sequence 3 assessment. You can nd the assessment

item bank and rubric in the Assessments section of GLOBE Weather.

Assessment

This nal individually

written explanation

can serve as one of the

summative assessments

for this learning sequence.

A CURVEBALL: When air and storms move, why do they curve?

Storyline Link

Students are motivated to

gather more evidence to

explain the phenomenon.

STEP 3

STEP 2

LOOK

BACK

GLOBE Weather | LS3: Worldwide Weather

129

| TEACHER GUIDE

GLOBE Temperature and Latitude Data Cards: Page 1

NOTE: Cut apart the graphs and maps on the following four pages for each student group. (Use the

highest/lowest temperature cards if students need support to interpret graphs.)

GLOBE Weather | LS3: Worldwide Weather

130

| TEACHER GUIDE

GLOBE Temperature and Latitude Data Cards: Page 2

GLOBE Weather | LS3: Worldwide Weather

131

| TEACHER GUIDE

GLOBE Temperature and Latitude Data Cards: Page 3

Location:

Saudi Arabia

Latitude:

21.3725

Distance from

the equator:

2,372 km

Location:

Sri Lanka

Latitude:

7.1438

Distance from

the equator:

793 km

Location:

Finland

Latitude:

63.2377

Distance from

the equator:

7,020 km

Polar

Midlatitudes

Tropics

equator

Polar

Midlatitudes

Tropics

equator

Polar

Midlatitudes

Tropics

equator

GLOBE Weather | LS3: Worldwide Weather

132

| TEACHER GUIDE

GLOBE Temperature and Latitude Data Cards: Page 4

Location:

Vermont, US

Latitude:

44.675

Distance from

the equator:

4,959 km

Location:

Arizona, US

Latitude:

36.4493

Distance from

the equator:

4,046 km

Polar

Midlatitudes

Tropics

equator

Polar

Midlatitudes

Tropics

equator