Air Masses & Fronts. What is an AIR MASS? An air mass is a huge body of air that influences...

Air Masses & Fronts

What is an AIR MASS?

• An air mass is a huge body of air that influences weather.

• Scientists classify air masses based on: TEMPERATURE and HUMIDITY

Air Masses are named based on where they FORMED…

= TROPICAL

= POLAR

= MARITIME (means sea…

wet)

= CONTINENTAL (means land… dry)

How are Air Masses named?

MARITIME

TROPICAL

MARITIME

POLAR

CONTINENTAL

TROPICAL

CONTINENTAL

POLAR

North American Air Masses

MARITIME POLAR

CONTINENTAL POLAR

MARITIME POLAR

MARITIME TROPICAL

MARITIME TROPICAL

CONTINENTAL TROPICAL

How do these air masses move?

MARITIME POLAR

CONTINENTAL POLAR

MARITIME POLAR

MARITIME TROPICAL

MARITIME TROPICAL

CONTINENTAL TROPICAL

Jet Stream Jet Stream

Prevailing Westerlies

That’s why weather generally moves WEST to EAST

in the U.S.

What happens when air masses meet?

• Air masses don’t mix easily.• The line between air masses is called

a front.

COLD FRONTS

WARM FRONTS

Watch the BrainPop video on “Weather”

and write down 2 things you learned.

Use your textbook (pg.133-135) to fill out the chart.

Compare/Contrast Chart - Types of Fronts

Front How it Forms Type of Weather

Cold Front

A fast-moving cold air mass overtakes a warm air mass.

Clouds form. If warm air is humid, rain/snow may fall.Possible thunderstorms.

Warm Front

Stationary Front

Occluded Front

Compare/Contrast Chart - Types of Fronts

Front How it Forms Type of Weather

Cold Front

A fast-moving cold air mass overtakes a warm air mass.

Clouds form. If warm air is humid, rain/snow may fall.Possible thunderstorms.

Warm Front A warm air mass overtakes a slow-moving cold air mass.

Scattered clouds. Light rain or snow.May last several days.

Stationary Front

Occluded Front

Compare/Contrast Chart - Types of Fronts

Front How it Forms Type of Weather

Cold Front

A fast-moving cold air mass overtakes a warm air mass.

Clouds form. If warm air is humid, rain/snow may fall.Possible thunderstorms.

Warm Front A warm air mass overtakes a slow-moving cold air mass.

Scattered clouds. Light rain or snow.May last several days.

Stationary Front

Cold and warm air meet, but neither can move the other. Creates “standoff”

Rain, snow, clouds, or fog that may last for days.

Occluded Front

Compare/Contrast Chart - Types of Fronts

Front How it Forms Type of Weather

Cold Front

A fast-moving cold air mass overtakes a warm air mass.

Clouds form. If warm air is humid, rain/snow may fall.Possible thunderstorms.

Warm Front A warm air mass overtakes a slow-moving cold air mass.

Scattered clouds. Light rain or snow.May last several days.

Stationary Front Cold and warm air meet, but neither can move the other. Creates “standoff”

Rain, snow, clouds, or fog that may last for days.

Occluded Front

A warm air mass is caught between 2 cooler air masses. Warm air mass is pushed up.

Temperature gets cooler. Clouds and rain may form.

Surface Map (Fronts & Precipitation)

Stationary Front

Occluded FrontWarm Front

Cold Front

HHHigh Pressure

LLLow Pressure

Precipitation

Temperature Map

Stationary Front

Occluded FrontWarm Front

Cold Front

HHHigh Pressure

LLLow Pressure

30°C

14°C

15°C

12°C

28°C 21°C

20°C

26°C

25°C

19°C

Monday WeatherLittle Rock, AR

Sun & clear skiesCool = 15°C

Tuesday WeatherLittle Rock, AR

Clouds & RainWarmer = 21°C

Wednesday WeatherLittle Rock, AR

Partly SunnyWarmer = 26°C

Which direction is the warm front moving?

What will happen to the weather in Little Rock?

Stationary Front

Occluded FrontWarm Front

Cold Front

HHHigh Pressure

LLLow Pressure

18°C

10°C8°C

20°C

Thursday WeatherNashville, TN

Partly SunnyWarm = 20°C

15°C

11°C

10°C

10°C

Which direction is the cold front moving?

What will happen to the weather in Nashville?

Friday WeatherNashville, TN

ThunderstormsCooler = 15°C

Saturday WeatherNashville, TN

SunnyCool = 10°C