1. Air Masses and Fronts

2. What are air masses? Large Bodies of air
Form when the air over a large region sits in one place for many days
The air gradually takes on the characteristics of the land or water below it

3. How do air masses affect our weather?
As an air mass moves, it brings its characteristics with it
Changes weather
Weather changes where air masses meet

4. What are the two characteristics that describe air masses?
Two words each
One for moisture
One for temperature

5. When describing moisture what words can we use?
The first word of an air mass tells one where the mass was formed (over water or land)
Continental
Air masses formed over land
Air becomes dry as it loses moisture to the dry land below it
DRY
Maritime
Air masses formed over water
Air becomes wet as it gains water vapor from the water below it
WET

6. When describing temperature what words can we use?
The second word of an air mass tells whether an air mass was formed close to the equator or pole
Tropical
Air masses formed near the equator
Air becomes warm as it gains energy from the warm land or water
WARM AIR
Polar
Air masses formed closer to the poles
Air becomes cool as it loses energy to the cold land or water
COLD AIR

7. What are the 4 Major Air Masses?
The four major air masses are:
Maritime Tropical (moist warm air)
Continental Tropical (dry warm air)
Maritime Polar (moist cold air)
Continental Polar (dry cold air)

10. What do you think can move air masses?
Air masses can travel away from the regions where they form
Can move with global winds
Can move with jet streams
As the air mass moves it changes

11. What is it called when 2 air masses meet?
Fronts form between two air masses and clouds can form in this rising air

12. What are the four different types of fronts?
Different fronts = different weather
Four Front Types
Cold Front
Warm Front
Occluded Front – We wont focus on this one
Stationary Front

13. Describe cold fronts Move into regions quickly Mass of cold, dense air
Warmer air ahead of it is pushed upward and condenses
Produces tall cumulonimbus clouds with precipitation and heavy storms
Followed by cooler and clearer skies

17. Describe warm fronts Slower than cold fronts.
As the warm air moves in it gradually goes above the colder denser air.
Moisture in the warm air condenses, producing cloud-covered skies.
Cirrus clouds are a sign of a warm front approaching, followed by stratus clouds and then as it comes there will be many hours of rain or snow. After it passes the air is warmer

21. Describe stationary fronts
Occur when air masses first meet or when a cold or warm front stops moving.
The boundary between masses doesn’t move
The air in each mass can still move sideways along the front or upward.
Upward movement will produce cloudy skies.
Whatever front advances first decides which it will be