Air Masses and Weather Fronts

The study of weather is meteorology

• Someone who studies weather is called a meteorologist

Air Pressure and Weather

• High Pressure = Heavy Air holds down water vapor = no clouds = Sunny

• Low Pressure = Light Air, water vapor rises = Lots of clouds and rain

AIR MASS: -a body of air with a certain temperature and moisture level.

-Caused by where it formed.

• Where’s the Jet Stream? What’s the air feel like at the letters?

A

B

CD

E

F

C = Continental: the air came from over the land = air is DRYM = Maritime: the air came from over the ocean = air is WETP = Polar: the air came from near the poles = air is COLDT = Tropical: the air came from near the equator = air is HOT

Movement of Air Mass• 1. Air masses are pushed around by global winds. The global winds above the U.S. always blow

Northeast.• 2. Air masses are also pushed around by the

Jet Stream– Jet Stream= (fast moving stream of air over US)

changes it’s pattern of movement each day.

The movement of weatherand air masses depends onBoth of these factors.

Fronts• Front is the space between the

different air Mass.

• When air with different moisture/temp meet, the air within them doesn’t mix.

• At all fronts, warmer air gets pushed up Causing low pressure and clouds/rain.

• Normally have rain and Storms

4 Types of Fronts:

Warm Fronts• The area was cold, then warm air moved in to

that area.

• Warm Air Rises up to make clouds and light rain.

• Gets warmer.

Directio

n front is

movin

g

Cold Fronts• The area was warm, then cold air moves

in to that area.

• Causes lots of violent storms as air rises fast (thunderstorms and tornadoes)

• After front passes temperature gets cooler

Direction front is moving

Stationary Fronts• Warm and cold front run into each

other.• These fronts are stationary (don’t move) because they sit still for

many days with light rain.

Occluded Fronts • When a cold front (moving quickly) catches up to a

warm front (moving slowly)• Warm air is trapped between two bodies of cold air.

• Long periods of light rain.• Colder after front passes.

Direction front is moving

Quiz 1Describe the weather in Chicago right now and how it will

change over the next 2 days. Why?

Chicago

Quiz 2: Describe the weather in Reno right now and how it will change

over the next 2 days. Explain why.

Reno

Quiz 31. What type of pressure is over Denver? 2. What type of pressure is over Charlotte? 3. Why are the local winds blowing in Vegas and Oklahoma city?