Source Regions and Air Masses

​Source Regions and Air Masses

Earth Systems and Structures || Severe Weather

​Air Mass

• A large body of air where temperature and moisture content are similar throughout.

• Air masses form over large land or water masses.

• Moisture content and temperature are determined by the area over which the air mass is formed called a source region.

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Source Region

​Air masses are designated by a two letter system.

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The first letter indicates the moisture content.

• Continental forms over continents

• Maritime forms over oceans

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Multiple Choice

Air masses are designated by a two letter system. What are the 2 letters?

• AM

• PM

• CM

• SR

Multiple Select

Air masses are designated by a two letter system.

What does C stand for?

What does M stand for?

Select all that apply

• C stands for Condensation

• M stands for Marine

• C stands for Continental

• C Stands Continents

• M stands for Maritime

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• Means land.

• A Continental air mass forms over land.​

• These are dry​

​Continental

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• Means water.

• Maritime air masses form over water.

• These have more moisture content

​Maritime

The second letter represents temperature.

• Polar - Cold air masses

• Tropical - Warm air masses

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​Polar

• Polar means it forms over the poles.

• COLD

• Think of polar bear​

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​Tropical

• Form over the tropics (near the equator)

• WARM

• Places near the equator will tend to be warmer and thus have tropical temperatures.

Fill in the Blanks

​Whether an air mass is warm or cold depends on the temperature of the source region.

​4 types of air masses.

1. Tropical – warm air masses that form over the tropics.

2. Polar – cold air masses that form over the poles.

3. Maritime – air masses that form over the ocean (very humid)

4. Continental – form over land – (are dry)

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these 2 are temperature based

These 2 are moisture based

​There are three polar air masses that influence the weather in the United States.

• Continental polar

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• Maritime polar: over the North Pacific Ocean

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• Maritime polar: over the North Atlantic ocean

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​There are three warm air masses that influence the weather in the United States.

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• Maritime tropical: that develops over the Gulf of Mexico

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• Maritime tropical: that develops over the South Pacific Ocean

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• Continental tropical

Multiple Choice

What types of air masses would be colder?

• Maritime
• Continental
• Polar
• Tropical

Multiple Choice

A cold, dry air mass would be called - 

• continental tropic
• continental polar
• maritime polar
• continental maritime

Multiple Choice

Which type of weather is usually associated with a mP air mass?

• moist and cool

• dry and warm

• moist and warm

• dry and cool

Air moves from an area of high-pressure to an area of low-pressure.

• Low pressure causes clouds and precipitation.

• High pressure causes dry weather with sunshine or sunny skies and calm weather.

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• High pressure is caused by air masses being cooled

• low pressure is caused by air masses being warmed

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Subject | Subject

​In other words

When air pressure drops, it gets cooler, meaning that you will get the effects of low temperature.

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When air pressure increases, it gets warmer, meaning that you will get drier weather.

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These 2 cycle through, since they are a part of the water cycle. ​

low -> high -> low -> high ->low ........​

Multiple Choice

Which type of air pressure do clear skies indicate?

• high pressure

• low pressure

• zero pressure

• medium pressure

Multiple Choice

In the morning, Julian noticed that the air pressure reading on the barometer was beginning to drop. What kind of weather can he most likely expect in the evening?

• The weather will be cloudy with a chance of rain.

• The weather will be warmer with clear skies.

• The weather will be clear and windy.

• The weather will be sunny and cool.