MS-ESS2-6NGSS*ScienceEarth and Space ScienceGrades 6-8
MS-ESS2-6: Modeling Global Winds, Ocean Currents and Regional Climates
In plain English: MS-ESS2-6 is the NGSS middle school performance expectation that asks students to develop and use a model of how unequal heating and Earth's rotation set up global winds and ocean currents, and how these patterns shape regional climates. Students use diagrams, maps, globes and climate graphs. It is usually taught in grade 6, 7 or 8 Earth science.
Develop and use a model to describe how unequal heating and rotation of the Earth cause patterns of atmospheric and oceanic circulation that determine regional climates.
Clarification Statement: Emphasis is on how patterns vary by latitude, altitude, and geographic land distribution. Emphasis of atmospheric circulation is on the sunlight-driven latitudinal banding, the Coriolis effect, and resulting prevailing winds; emphasis of ocean circulation is on the transfer of heat by the global ocean convection cycle, which is constrained by the Coriolis effect and the outlines of continents. Examples of models can be diagrams, maps and globes, or digital representations.
Assessment Boundary: Assessment does not include the dynamics of the Coriolis effect.
Next Generation Science Standards · Disciplinary Core Idea: Earth's Systems · Official standard
Students develop and use models that explain why climates differ from place to place. Climate is the usual pattern of weather in a place over many years (scientists often use 30-year averages). Two causes set the big patterns. First, unequal heating: sunlight strikes the equator more directly than the poles, so the tropics take in more energy per square meter. Second, Earth's rotation: as Earth spins, moving air and water curve to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This curving is called the Coriolis effect. Together they make bands of rising and sinking air, steady prevailing winds (winds that blow from the same direction most of the time) and loops of ocean currents that carry heat from the tropics toward the poles. Latitude, altitude and the way land and ocean are arranged then shape each regional climate.
The NGSS Clarification Statement says: "Emphasis is on how patterns vary by latitude, altitude, and geographic land distribution. Emphasis of atmospheric circulation is on the sunlight-driven latitudinal banding, the Coriolis effect, and resulting prevailing winds; emphasis of ocean circulation is on the transfer of heat by the global ocean convection cycle, which is constrained by the Coriolis effect and the outlines of continents. Examples of models can be diagrams, maps and globes, or digital representations." The Assessment Boundary says: "Assessment does not include the dynamics of the Coriolis effect." So students describe which way moving air and water turn and use that in their models, but they do not explain the forces or compute the effect. Data sets marked invented are made up for teaching; values described as real are rounded published values.
Learning Objectives
By the end of this lesson, students will be able to:
Explain with a model why sunlight heats Earth unequally by latitude, and how that makes bands of rising and sinking air
Use the rule that Earth's rotation turns moving air and water (right in the Northern Hemisphere, left in the Southern) to predict prevailing winds and the direction of ocean current loops
Describe how ocean currents and the global ocean convection cycle carry heat, and how continents steer them
Use diagrams, maps, globes and climate data to explain or predict the climate of a region from its latitude, altitude, nearby currents and position on land
Prior Knowledge Required
Students should already be comfortable with:
How the angle of sunlight changes with the seasons in a model of the Earth and sun MS-ESS1-1
Air moving from high pressure toward low pressure, and air masses carrying their weather MS-ESS2-5
Warm air or water rises and cooler, denser air or water sinks (convection)
Latitude lines on a map or globe, and reading a line graph
Show a globe and point to two real places: a lowland rain forest near the equator and a large desert near 25°N. Ask students to predict before showing any data:
Warm-Up Prompt
"Both places get strong sunshine. Why is one of them wet almost every day and the other dry almost every day? Sketch where you think the air is moving up or down over each place."
Collect sketches. Many students think deserts are dry only because they are hot; ask what happens to the water vapor in air that rises and cools (from MS-ESS2-4). Keep the sketches to compare with Diagram 1 at the end of the lesson.
Direct Instruction15 minutes
Unequal heating makes bands. Near the equator, the noon sun is high and its light is concentrated; near the poles, the same light spreads over more ground. Warm air near the equator rises, cools and drops its water as heavy rain. High up, it spreads toward the poles and sinks again near 30° latitude, where it warms and dries the land below. Near 60°, air rises again where cold polar air meets milder air, and at the poles cold air sinks. Diagram 1 shows these loops of rising and sinking air in both hemispheres.
Rotation turns the winds. Surface air flows back along the ground to fill the low pressure where air rises. Because Earth rotates, this moving air curves (the Coriolis effect): to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. That gives three belts of prevailing winds in each hemisphere: the trade winds (from the east, between the equator and 30°), the westerlies (from the west, between 30° and 60°) and the polar easterlies.
Oceans carry heat. Prevailing winds push the surface of the ocean. The currents curve the same way the winds do and are blocked and steered by the continents, so each ocean basin has a large loop of currents called a gyre. Currents flowing away from the tropics carry warm water toward the poles, and currents flowing toward the equator carry cold water. Deep down, the global ocean convection cycle moves water slowly around the world: in the far North Atlantic and around Antarctica, surface water becomes very cold and salty, so it is denser, sinks and spreads along the ocean floor, and rises again in other oceans. A full trip takes on the order of 1,000 years. Use Diagram 2 for the North Atlantic.
Altitude and land. Air cools on average about 6.5 °C for every 1,000 m of height, so mountains are colder than lowlands at the same latitude. Water heats up and cools down more slowly than land.
Unequal heating: the same beam, more ground
At noon on an equinox (around March 20 or September 22), a beam of sunlight with a 1 m² cross-section reaches the ground. Near the equator the sun is straight overhead, and the beam lights 1 m² of ground. Near 60°N the sun is 30° above the horizon, and the same beam lights 2 m².
Result: Each square meter at 60°N gets 1 ÷ 2 = one half as much energy as at the equator. Less energy per square meter means cooler ground and cooler air, which is why average temperatures fall toward the poles.
Latitude bands: rain forests and deserts
Large rain forests lie near the equator (the Amazon and Congo basins). Many large deserts lie roughly between 20° and 30° north or south (the Sahara, the Arabian Desert, the Kalahari and the deserts of central Australia).
Result: Rising air near the equator cools and its water vapor condenses into clouds and rain nearly every day. The same air sinks near 30°, warms as it sinks and makes clouds and rain rare. The bands come from unequal heating.
Rotation: trade winds and westerlies
In the Northern Hemisphere, surface air flows from the sinking zone near 30°N toward the rising zone at the equator, and also from 30°N toward 60°N.
Result: Air moving south toward the equator is turned to the right (toward the west), so it blows from the northeast: the northeast trade winds. Air moving north toward 60°N is turned to the right (toward the east), so it blows from the west: the westerlies. Sailing ships once crossed the Atlantic westward in the trade winds and returned eastward in the westerlies.
Ocean currents: the Gulf Stream
The Gulf Stream carries warm water from the tropics north along the east coast of the United States, then northeast across the Atlantic as the North Atlantic Current. Near Florida its surface water moves about 1.5 m/s or more.
Result: 1.5 m/s × 3,600 s = 5,400 m, about 5.4 km per hour, a little faster than a typical walk (about 5 km/h). The trade winds and westerlies push it, rotation turns it to the right, and the coast of North America steers it.
Altitude and land: a rain shadow
Westerly winds from an ocean cross a mountain range (invented data). A town on the windward (west) slope gets 2,400 mm of precipitation a year; a town in the valley on the east side gets 300 mm.
Result: 2,400 ÷ 300 = 8 times as much. Air forced up the west slope cools, its water vapor condenses, and rain and snow fall. The air then sinks down the east side, warms and dries: a rain shadow. The Cascade Range in Washington State shows this pattern, with much wetter western slopes.
After each example, ask: "Is this pattern caused mainly by unequal heating, by rotation, or by the shape of the land and ocean? Where would you draw it on Diagram 1 or Diagram 2?"
Guided Practice10-15 minutes
Pairs graph invented climate data for eight lowland towns along one line of longitude on an imaginary continent, from the equator to 70°N. They make one graph of temperature against latitude and one bar graph of precipitation against latitude, a digital or paper visualization of the data.
Guided practice data (invented): eight lowland towns from 0° to 70°N
Latitude
Average yearly temperature (°C)
Yearly precipitation (mm)
0°
26
2,600
10°N
26
1,700
20°N
24
700
30°N
20
200
40°N
14
650
50°N
8
950
60°N
1
750
70°N
-9
300
How much colder is the town at 70°N than the town at the equator? On average, how many degrees colder is each step of 10° in latitude?
Which latitude is driest, and which two latitudes are the wettest?
Line up your precipitation graph with Diagram 1. Label each wet latitude "rising air" or "sinking air", and do the same for the driest latitude.
Write two sentences: one that uses unequal heating to explain the temperature pattern and one that uses rising and sinking air to explain the precipitation pattern.
Debrief: ask pairs to compare their labels with Diagram 1 and to explain any latitude that does not fit the bands. Point out that real places also depend on altitude, currents and mountains, which the next phase adds.
Independent Practice10-15 minutes
Each student uses Diagram 1, Diagram 2 and a globe to predict the climate of three invented places, writing for each one the expected temperature pattern, the expected precipitation and the parts of the model that explain them:
Place P: a lowland at 5°S, far from mountains.
Place Q: a coastal town at 26°N on the west coast of Africa, beside the Canary Current.
Place R: a town at 65°N on the coast, where the wind usually comes from the land.
For one of the three places, name a change (a mountain range, a different current, a move inland) that would change its climate, and predict the new climate.
Circulate and ask each student to point to the arrow on a diagram that supports each prediction. Students keep their predictions for the exit ticket.
Closure5 minutes
Exit ticket: "Name one way unequal heating and one way Earth's rotation shape the climate where you live. Use a prevailing wind, an ocean current or a band of rising or sinking air in your answer." Return to the warm-up sketches and ask students to correct them with the loops of Diagram 1.
Differentiation Strategies
For Struggling Students
Give a copy of Diagram 1 with blank labels and a word bank (rising air, sinking air, trade winds, westerlies, polar easterlies)
Use a hand signal for the turning rule: in the Northern Hemisphere, point the way the air starts to move and then turn your hand to the right
Start the map work with one ocean basin and two currents before adding the rest
For Advanced Students
Ask students to predict how the gyres would look if Earth rotated the other way, and to explain each change
Have students compare real climate graphs for two cities at the same latitude on opposite sides of an ocean, using an online climate data tool
Ask students to explain why the band of rising air near the equator shifts north and south with the seasons
Assessment Guidance
What to Look For
Check that students link each pattern to its cause: bands of rising and sinking air to unequal heating, the turning of winds and currents to rotation, and the steering of currents to the shapes of continents. Look for models that show surface winds and aloft winds moving in opposite directions within each loop. Listen for the idea that currents carry heat from the tropics toward the poles. Students do not need to explain why rotation turns moving air; they need to use the direction of the turn.
02
Classroom Activities
3 Activities
1
Spinning Plate: How Rotation Bends a Path
20 minPairs
Pairs model the Coriolis effect with a paper plate that spins on a pencil. One partner turns the plate while the other draws a line with a ruler straight out from the center. The line is straight in the room, but on the plate it curves, just as winds and currents curve on the rotating Earth.
Procedure
Push a sharpened pencil up through the center of a paper plate from below so the plate can turn on it, and hold the pencil steady on the desk. Mark a dot at the center and a start mark on the rim.
Look down at the plate. Partner 1 turns it counterclockwise, as Earth turns when seen from above the North Pole, at a steady one full turn in 16 s.
Partner 2 holds a ruler fixed in place on the desk and, in 2 s, draws a line along it from the center toward the start mark.
Stop and look at the line. Measure, with a protractor at the center, the angle between the start mark and the point where the line reaches the rim.
Repeat at one full turn in 8 s. Use a fresh plate for each trial.
Safety: keep the sharpened pencil point facing down into the desk, and do not spin the plate fast enough to fly off.
Sample Data (invented)
Slow spin (one turn in 16 s): the line curves, and its end lands 45° around the rim from the start mark. Fast spin (one turn in 8 s): the end lands 90° around the rim. In both trials, the line on the plate bends to the right of the direction the pen moved.
Discussion Questions
The pen moved in a straight line over the desk. Why does the line on the plate curve?
How did spinning twice as fast change the angle? Use the sample data.
On Diagram 1, find two surface winds in the Northern Hemisphere. Does each one curve the same way as your line?
How would you change the model to show the Southern Hemisphere? Predict, then test it.
Modification for Distance Learning
Students use a free online rotating-disk simulation, or a paper plate on a pencil at home, and post a photo of their curved lines with the direction of rotation labeled.
2
Map and Globe Model: Winds, Currents and Heat
25 minGroups of 3
Groups build a conceptual model on a blank world map, checking each step on a globe. They start with sunlight and latitude bands, add winds and ocean currents, and finish by predicting the climate at six lettered points on the coasts.
Procedure
Step 1: draw the equator and the 30° and 60° lines in both hemispheres. Shade the bands where air rises (wet) and where it sinks (dry), using Diagram 1.
Step 2: draw the three prevailing winds in each hemisphere as arrows, curved the correct way.
Step 3: in each ocean basin, draw the surface currents that the winds would push. Let the continents block and steer them. Color currents moving toward the poles red (warm) and currents moving toward the equator blue (cold).
Step 4: mark the two regions where cold, salty water sinks to start the global ocean convection cycle, and draw a dashed arrow for the deep return flow.
Step 5: the teacher marks six coastal points, A to F, at different latitudes on both sides of the oceans. For each point, predict "warm or cool for its latitude" and "wet or dry", and name the part of the model you used.
Discussion Questions
Which way does your gyre turn in the North Pacific and in the South Pacific? Where on your map did a continent change the direction of a current?
Compare two of your points at about the same latitude on opposite sides of one ocean. Which one did you predict to be warmer, and why?
Where does your model show heat moving from the tropics toward the poles? List one wind and one current.
What does a flat map show less well than a globe?
Modification for Distance Learning
Groups build the model on a shared digital map with drawing tools, then compare it with an online map of real ocean currents and note one difference.
3
Climate Graph Match: A Digital Representation
25 minPairs
Pairs enter invented climate data for four places into a spreadsheet, make a climate graph for each (monthly temperature as a line, yearly precipitation in the title), and match each graph to a location using the model. Then they use an online globe or climate map to find a real place in a similar location and compare.
Climate Data (invented)
Place W: every month between 26 and 28 °C; 2,600 mm of precipitation a year, with rain in every month.
Place X: January 14 °C, July 33 °C; 60 mm a year.
Place Y: January 6 °C, July 16 °C; 1,200 mm a year, most of it in winter.
Place Z: January -12 °C, July 22 °C; 600 mm a year, most of it in summer.
Locations to Match
Location 1: a coastal lowland at 2°N.
Location 2: the interior of a large continent at 24°N.
Location 3: a west coast at 48°N, with the ocean upwind.
Location 4: the interior of a large continent at 48°N, far from any ocean.
Procedure
Enter the data and make the four graphs. Find each place's yearly range: July temperature minus January temperature.
Match each place to a location and write one sentence for each match that names the part of the model you used (latitude band, prevailing wind, ocean or land, current).
On the online globe, find one real place near each location and look up its climate. Record whether it fits your match.
Discussion Questions
Places Y and Z are at the same latitude. Why are their yearly ranges so different?
Which place has the smallest yearly range, and why?
Which match was hardest? What other data would help you decide?
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: A Model of Global Atmospheric Circulation
A model of Earth's global circulation (not to scale; the loops are drawn far taller than the real atmosphere, which is only about 8-16 km deep where they turn). Unequal heating makes air rise near the equator and near 60° and sink near 30° and at the poles, forming three loops in each hemisphere. Surface winds in each band are turned by Earth's rotation, giving the trade winds, westerlies and polar easterlies.
Diagram 2: Surface Currents of the North Atlantic
A simplified map of the main surface currents of the North Atlantic (shapes and distances are not to scale). The trade winds and westerlies push the surface water, rotation turns it, and the continents steer it, so the currents form a clockwise loop. Red arrows carry warm water away from the tropics; blue arrows carry cold water toward the equator.
04
Homework Assignment
~30 min
MS-ESS2-6 Homework: Using Models of Circulation and Climate
Directions: Use Diagram 1, Diagram 2 and your map model. Data marked invented are made up for practice. For each problem, name the part of the model you use (unequal heating, rotation, a prevailing wind, an ocean current, altitude or the position of land and ocean) and show calculations with units.
Part 1: Building and Using Models (Problems 1-3)
A classmate's model of global circulation has three mistakes: (1) it labels the band near 30°N "rising air, rain forests"; (2) it draws the trade winds of the Southern Hemisphere blowing from the northeast; (3) its caption says "the sun heats all latitudes equally, but the poles are cold because they are far from the sun." For each mistake, explain what is wrong and write the corrected label or sentence.
Invented data: the same small solar panel lies flat on the ground at noon on an equinox, in clear weather, at three schools. It produces 9.0 W near the equator, 6.9 W at 40°N and 3.1 W at 70°N. (a) Find each value as a percent of the equator value. (b) Use the idea of sunlight spreading over more ground to explain the pattern. (c) Predict how the average temperature changes from the equator to 70°N, and explain.
Peru is on the west coast of South America, between about 3°S and 18°S. A digital map of sea surface temperature shows water near the Peruvian coast several degrees colder than the open ocean farther west at the same latitude. (a) Use the turning rule for the Southern Hemisphere and the outline of South America to explain which way the ocean current along this coast flows and why its water is cold. (b) Predict two features of the coastal climate, and explain each one with the model.
Part 2: Climate Data (Problems 4-6)
Invented data: a town at 200 m above sea level has an average yearly temperature of 24 °C. Use the average cooling of 6.5 °C per 1,000 m. (a) Predict the average temperature of a village 2,200 m above sea level on the same mountain. (b) At about what height would the average temperature be 0 °C? (c) Why can a mountain near the equator have snow on top all year?
Invented data: westerly winds cross a mountain range. The yearly precipitation from west to east is 1,500 mm at the coast, 2,800 mm on the west slope, 3,200 mm near the crest, 600 mm on the east slope and 250 mm in the valley east of the range. (a) How many times as much precipitation falls on the west slope as in the east valley? (b) Explain the pattern with a labeled sketch of the air moving over the range. (c) Predict how the pattern would look if the prevailing wind came from the east.
A student claims: "Places at the same latitude always have the same climate." Write a claim, evidence and reasoning response. Use at least two kinds of evidence from this lesson (for example, ocean currents, mountains or distance from the ocean).
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Model
Uses the correct bands, winds, turning direction and currents, with labels
Model is mostly right but one band, wind or current is wrong
Causes
Links each pattern to unequal heating, rotation, altitude or the land and ocean
Describes the pattern without naming its cause
Calculations
Percents, temperatures, heights and ratios are correct, with units
Method is right but one value or unit is wrong
Evidence
Uses data or a specific place as evidence for each claim
Gives claims without evidence
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Use Diagram 1, Diagram 2 and your map model. Data marked invented are made up for practice. Your score updates as you answer, and Reset quiz clears everything so you or your students can try again.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
Why is the average temperature at 70°N much lower than at 10°N?
Answer: B
At high latitudes the sun is lower in the sky, so each beam of sunlight spreads over more ground and each square meter gets less energy. Choice A is wrong because the sun shines equally in all directions. Choice C is wrong because the distance from the sun is nearly the same for all of Earth, and it is not what makes the poles cold. Choice D reverses what currents do: warm currents carry heat toward high latitudes.
Question 2 of 20 · Multiple Choice
Satellite pictures show a belt with very few clouds near 30°S over several continents and oceans. Which part of the circulation model explains this belt?
Answer: A
Near 30° the air that rose at the equator sinks. Sinking air warms, so its water vapor does not condense, and clouds and rain are rare. Choice B describes the equator and 60°, where air rises. Choice C is wrong because winds move clouds but do not stop them from forming across a whole belt. Choice D is wrong because evaporation still happens over cold water, and the belt also covers warm oceans.
Question 3 of 20 · Multiple Choice
In the Southern Hemisphere, surface air flows from near 30°S toward 60°S, and Earth's rotation turns it to the left. From which direction does the resulting wind blow?
Answer: C
Air moving south (toward the South Pole) that turns to its left ends up moving toward the east, so it blows from the west: the westerlies of the Southern Hemisphere. Choice A turns the air to the right, the Northern Hemisphere rule. Choice B reverses the direction of motion. Choice D leaves out the effect of rotation.
Question 4 of 20 · Multiple Choice
Which way do the main surface currents of the North Pacific Ocean flow around the basin?
Answer: A
The North Pacific is in the same hemisphere as the North Atlantic: the trade winds and westerlies push the water, rotation turns it to the right, and the coasts of Asia and North America close the loop, so it turns clockwise, as in Diagram 2. Choice B uses the Southern Hemisphere rule. Choices C and D ignore the continents, which block and steer the currents into a loop.
Question 5 of 20 · Multiple Choice
Much more of the Southern Hemisphere is ocean than the Northern Hemisphere. Which prediction follows from the model?
Answer: C
Water heats up and cools down more slowly than land, so a hemisphere with more ocean has smaller differences between summer and winter. Choice B reverses the effect of the ocean. Choice A is wrong because the two hemispheres receive the same sunlight over a year. Choice D confuses the effect of land and ocean with the effect of rotation.
Question 6 of 20 · Multiple Choice
On a tall tropical island, the trade winds blow from the northeast almost every day. Where on the island is the driest land most likely to be?
Answer: A
Air forced up the northeast (windward) slopes cools and drops its water as rain. It then sinks down the southwest side, warms and dries, making a rain shadow. Choice B is the wet, windward side. Choice C is the windward slopes, where rising air cools and drops the most rain. Choice D ignores how mountains lift the air.
Question 7 of 20 · Multiple Choice
Invented data: a town at 300 m above sea level averages 27 °C. Using the average cooling of 6.5 °C per 1,000 m, what is the predicted average at a station 2,300 m above sea level on the same mountain?
Answer: D
The station is 2,300 - 300 = 2,000 m higher, so it is 2 × 6.5 = 13 °C cooler: 27 - 13 = 14 °C. Choice A adds the 13 °C instead of subtracting. Choice B subtracts only 6.5 °C, the cooling for 1,000 m. Choice C uses the full 2,300 m (27 - 15 = 12) instead of the difference in height.
Question 8 of 20 · Multiple Choice
A student freezes salty water dyed blue into an ice cube and floats it in a clear tank of room-temperature fresh water. As it melts, streams of blue water sink to the bottom. Which part of Earth does this model?
Answer: B
The meltwater is cold and salty, so it is denser than the water around it and sinks, as surface water does in the far North Atlantic and around Antarctica. That sinking drives the global ocean convection cycle. Choice A is the opposite motion. Choices C and D add fresh water at the surface, which tends to stay on top rather than sink.
Question 9 of 20 · Multiple Choice
A paper plate turns clockwise when seen from above. A line drawn straight out from the center curves to the left of the direction of motion. Which part of Earth does this spinning plate model?
Answer: C
Seen from above the South Pole, Earth turns clockwise, and moving air and water there curve to the left. Choice B is modeled by a plate turning counterclockwise, with paths curving to the right. Choice A is wrong because the turning effect is weakest near the equator and changes direction across it. Choice D is wrong because the two hemispheres curve in opposite directions.
Question 10 of 20 · Multiple Choice
In most of the United States, storms and other weather systems usually move from west to east. Which part of the circulation model explains this?
Answer: D
Most of the United States lies between about 30°N and 50°N, the band of the westerlies, which blow from the west and carry weather systems toward the east. Choice A blows from the east and lies closer to the equator. Choice C blows from the east near the poles. Choice B is an ocean current, which does not steer storms across the land.
Question 11 of 20 · Multiple Choice
Invented data: a lowland town has an average yearly temperature of 22 °C and only 120 mm of precipitation a year. At which latitude is it most likely to be?
Answer: B
Warm but very dry fits the band of sinking air near 30°, where many deserts lie. Choice A is in the band of rising air, which is rainy all year. Choice C is in the stormy westerlies and too cool for a 22 °C average. Choice D is far too cold.
Question 12 of 20 · Multiple Choice
At noon, a beam of sunlight delivers 1,000 W to 1 m² of ground near the equator. Near the Arctic Circle, the same beam spreads over 2.5 m² of ground. How much power does each square meter there receive?
Answer: D
1,000 W ÷ 2.5 m² = 400 W per square meter. Choice A multiplies instead of dividing. Choice B subtracts 2.5 from 1,000. Choice C is 1,000 - 400, the power each square meter loses compared with the equator, not what it receives.
Question 13 of 20 · Multiple Choice
Suppose Earth stopped rotating but was still heated unequally. How would the surface winds near 15°N change?
Answer: D
Unequal heating would still make air rise at the equator and sink farther north, so surface air would still flow toward the equator, but without rotation it would not be turned to the west. Choice A ignores unequal heating, which still drives the flow. Choice B reverses the direction of the surface flow. Choice C describes the westerlies, which also depend on rotation.
Question 14 of 20 · Multiple Choice
Scientists study whether the North Atlantic Current could slow down. If it carried less warm water, where would winter temperatures most likely drop?
Answer: B
The North Atlantic Current carries warm water from the Gulf Stream toward northwest Europe and helps give the region milder winters than other places at its latitude. Choice A is where the warm water starts, so it would not lose the heat it carries away. Choices C and D are not on the path of this current.
Question 15 of 20 · Short Answer
Two invented coastal towns are both at 40°N, and the prevailing winds there are westerlies. Town East is on the east coast of a continent, beside a warm current. Town West is on the west coast of a continent, beside a cold current. Predict which town has warmer ocean water in summer and which has milder winters, and explain both predictions with the model.
Warmer summer ocean water: Town East, because its warm current carries water from the tropics toward the pole. Milder winters: Town West, because the westerlies reach it after crossing the ocean, which cools slowly in winter, while they reach Town East after crossing a cold continent. The cold current also gives Town West cool summers. Look for both a current and the prevailing wind in the explanation.
Question 16 of 20 · Short Answer
Predict how the trade winds of the Northern Hemisphere and the North Atlantic gyre would change if Earth rotated in the opposite direction. Explain your reasoning.
Model answer: Moving air and water in the Northern Hemisphere would curve to the left instead of the right. Air flowing south toward the equator would turn toward the east, so the trade winds would blow from the northwest instead of the northeast. The winds and the turning would both push the North Atlantic currents the other way, so the gyre would turn counterclockwise, and warm currents would run along different coasts. Unequal heating would still make air rise at the equator and sink near 30°.
Question 17 of 20 · Short Answer
A drifting buoy is carried by the North Atlantic Current at an average of 0.25 m/s. (a) How far does it travel in one day, in km? (b) About how many days would it take to travel 3,000 km toward Europe? (c) What does the buoy carry with it besides water, and why does that matter for climate?
(a) 0.25 m/s × 86,400 s = 21,600 m ≈ 22 km per day. (b) 3,000 ÷ 21.6 ≈ 139 days, about 4 to 5 months. (c) The water carries heat from the tropics toward higher latitudes, which warms the air over the ocean and the coasts downwind.
Question 18 of 20 · Short Answer
A student says: "The winds near the equator must always be very strong, because the sun heats that region the most." Use the model to evaluate this claim.
Model answer: The claim is not supported. Near the equator, the strong heating makes air rise, so most of the motion is upward, not sideways along the ground, and surface winds there are often light. The steady trade winds blow on either side of this belt, where surface air flows toward the equator from the sinking zones near 30°. Sailors long called the calm equatorial belt the doldrums.
Question 19 of 20 · Short Answer
Plan how you would use an online climate data tool or digital globe to test the claim that two places at the same latitude can have very different climates. Name two places you would compare, the data you would look up, and the pattern that would support the claim.
Model answer: Compare a place on a west coast with the ocean upwind and a place far inland at the same latitude (for example, a coastal city and an inland city both near 47°N in North America). Look up the average temperature for every month and the yearly precipitation, and graph them. The claim is supported if the coastal place has a much smaller difference between summer and winter and a different amount of precipitation. Look for the same latitude, a clear difference in position (ocean, mountains or currents), and named data.
Question 20 of 20 · Short Answer
Invented data: a coastal town has an average January temperature of 7 °C and July temperature of 16 °C. An inland town at the same latitude has -10 °C in January and 24 °C in July. (a) Find each town's yearly range. (b) Explain the difference with the model.
(a) Coastal: 16 - 7 = 9 °C. Inland: 24 - (-10) = 34 °C. (b) Water heats up and cools down more slowly than land, so air over the nearby ocean stays mild in both seasons and keeps the coastal town's temperatures close together. The inland town is far from that effect: the land heats strongly in summer and cools strongly in winter.
0 of 20 answered · 0 correct
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Frequently Asked Questions
10 Questions
What does MS-ESS2-6 mean?
MS-ESS2-6 asks middle school students to develop and use a model of how unequal heating and Earth's rotation cause patterns in the atmosphere and oceans, and how those patterns determine regional climates. The code stands for Middle School, Earth and Space Science, core idea 2 (Earth's Systems), performance expectation 6.
What grade is MS-ESS2-6 taught in?
It can be taught in grade 6, 7 or 8, since NGSS writes middle school standards for the grade 6-8 band and each state or district sets the order. It usually comes after MS-ESS2-4 (the water cycle) and MS-ESS2-5 (air masses and weather) in a weather and climate unit.
What is the assessment boundary for MS-ESS2-6?
Assessment does not include the dynamics of the Coriolis effect. Students should know and use the direction of the turn (right in the Northern Hemisphere, left in the Southern) to predict winds and currents, but they are not asked to explain the forces behind it or to calculate it.
What is the Coriolis effect, in simple words?
It is the curving of moving air and water that we see because Earth rotates under them. A wind or current that starts out straight ends up bending to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The paper plate model shows the same kind of curving.
What is the difference between weather and climate?
Weather is the condition of the air at one place and time, which can change within hours. Climate is the usual pattern of weather in a place over many years, often described with 30-year averages of temperature and precipitation for each month.
Why do ocean currents move in loops?
Prevailing winds push the ocean surface, rotation turns the moving water, and the continents block and steer it. Together these make a large loop of currents, called a gyre, in each ocean basin. Diagram 2 shows the gyre of the North Atlantic.
What is the global ocean convection cycle?
It is the slow movement of water through the deep ocean. Where surface water becomes very cold and salty, it becomes denser and sinks, then spreads along the ocean floor and eventually rises in other oceans. It moves heat around the planet over hundreds to about a thousand years, much more slowly than the wind-driven surface currents.
How do mountains change climate?
Air gets cooler with height, by about 6.5 °C per 1,000 m on average, so high places are colder than lowlands at the same latitude. Mountains also force moving air upward, which cools it and makes rain or snow on the side facing the wind, leaving a drier rain shadow on the other side.
What models can students use for MS-ESS2-6?
The Clarification Statement names diagrams, maps and globes, and digital representations. This page uses a circulation diagram, a current map, a globe with a blank world map, a spinning plate for the Coriolis effect, and climate graphs made in a spreadsheet or viewed on an online globe.
How does MS-ESS2-6 connect to high school science?
It prepares students for HS-ESS2-4, where they model how changes in the flow of energy into and out of Earth's systems change climate, and for high school study of climate change. In middle school it builds on MS-ESS2-5 (air masses and weather) and connects to MS-ESS3-5 on the rise in global temperatures.
07
Related Standards
5 standards
These standards connect to MS-ESS2-6: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
3-ESS2-2Prerequisite
Obtain and combine information to describe climates in different regions of the world
Lesson coming soon
MS-ESS1-1Prerequisite
Model the Earth-sun-moon system to describe moon phases, eclipses and seasons
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