Living By Chemistry Teaching and Classroom Resources Unit 3 Weather 221 © 2012 W. H. Freeman and Company/BFW Lesson 7 •Worksheet

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Front and Center Density, Temperature, and Fronts

Name

Date Period

PurposeTo investigate how fronts affect the weather.

Part 1: Weather MapsReexamine the weather maps from Lesson 1 to answer the questions.

1. Examine the Fronts Map, Cloud Cover Map, and Precipitation Map together. What relationships do you see among fronts, clouds, and precipitation?

2. Where would you expect to see warm and cold air masses on the Fronts Map? Draw them on this map.

Cold air Warmair

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L E S S O N

7AcTIvITy

Part 2: Warm and Cold Fronts 1. Why is a cold air mass denser than a warm air mass?

2. Explain why clouds might form when a warm air mass collides with a cold air mass.

3. Examine the illustration showing what happens at a cold front.

Coldfront:Coldairovertakeswarm air.

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222 Unit 3 Weather Living By Chemistry Teaching and Classroom Resources Lesson7•Worksheet © 2012 W. H. Freeman and Company/BFW

a. Explain why warm air is pushed up by the cold front.

b. Where do clouds form when there is a cold front?

c. Where does precipitation fall when there is a cold front?

4. Examine the illustration showing what happens at a warm front.

a. What happens to the warm air when it overtakes the cold air?

b. Where do clouds form when there is a warm front?

c. Where does precipitation fall when there is a warm front?

5. Making Sense What does air density have to do with weather fronts?

6. If You Finish Early Nearly eighty percent of the air in our atmosphere is nitrogen gas, N2, while water vapor makes up only 1% of the air. Why doesn’t it rain liquid nitrogen instead of rainwater?

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Warm air Coldair

Warmfront:Warmairovertakescoldair.

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Living By Chemistry Teaching and Classroom Resources Unit 3 Weather 223 © 2012 W. H. Freeman and Company/BFW Lesson 7 • Transparency

ChemCatalystLarge air masses form over different regions of land and ocean. These air masses have a consistent temperature and moisture content.

1. What patterns do you notice in the temperatures and moisture content of the air masses shown on the map?

2. Why do you think clouds form when the Continental Polar air mass collides with the Maritime Polar air mass?

3. Use the concept of density to explain why warm air in the Maritime Polar air mass rises, while cold air in the Continental Polar air mass descends.

Maritime Polar

cool, moist

Continental Polarcold, dry

Continental Arcticbitterly cold, dry

MaritimePolar

cool, moist

Maritime Tropical

warm, moist

ContinentalTropicalhot, dry Maritime Tropical

warm, moist

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224 Unit 3 Weather Living By Chemistry Teaching and Classroom Resources Lesson7•Transparency © 2012 W. H. Freeman and Company/BFW

Fronts

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Cold air Warmair

Warm air Coldair

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Coldfront:Coldairovertakeswarmair.

Warmfront:Warmairovertakescoldair.

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