1. Air Masses and Weather

2. Origin of an Air Mass
Air Mass: A large body of air in the lower troposphere that has similar characteristics throughout
Characteristics:
Several kilometers in diameter
Several kilometers high
Temperature and humidity are nearly uniform throughout an air mass

3. What type of characteristics does as air mass have throughout?
Similar

4. Temperature and Moisture Level
These characteristics depend on where the air mass originates.
Ex: if an air mass stays in a polar region for an extended period of time, it becomes cold as well.
When an air mass travels from one area to another, it takes with it the temperature and humidity of its place of origin
As it travels, its characteristics may change

5. What happens when an air mass travels?
it takes with it the temperature and humidity of its place of origin

6. Types of Air Masses
Classification of air masses is based on their place of origin
The names are two part:
Temperature- arctic, polar, or tropical region
Humidity- land (continental) or marine (maritime)

7. What two characteristics are used to classify air masses?
Temperature and humidity

8. Continental Arctic Originate in Arctic regions
Air becomes extremely cold
Capable of causing extreme cold waves as they move into new regions
Very dry

9. Continental Polar
Originate over the inland regions of Alaska and Canada
Slightly warmer than Continental Arctic
Usually dry
If travels over large body of water, can create precipitation

10. Maritime Polar Originate over the ocean in high latitudes
Cold and damp
Produces fog, clouds, and precipitation
“nor’easters” heavy snowstorms from the North Atlantic

11. Maritime Tropical Originate over a warm tropical ocean Warm and moist
Produce thunderstorms in the heat of the day

12. Continental Tropical Originate over deserts Hot and dry
Produce tremendous heat waves

14. What are the 5 types of air masses?
Continental Arctic, Continental Polar, Maritime Polar, Maritime Tropical, and Continental Tropical

15. Fronts

16. Fronts Front: The boundary that separates opposing air masses
Characteristics
Width: 200 meters to 200 Kilometers
Height: up to 5 kilometers
Length: up to 2000 kilometers
Usually bring precipitation
Most common at mid latitudes
Where polar and tropical air masses meet

17. The boundary that separates opposing air masses
What is a front?
The boundary that separates opposing air masses

18. Shape of a front
The less dense air mass is forced to rise over the denser air mass. This makes the front wedge shaped.

19. Cold Front
Boundary between an advancing cold air mass and the warmer air mass it is displacing
Steep slope
Narrow band of precipitation
Moves quickly

20. Warm Front Warm air displaces cold air Gradual slope Cirrus clouds
Steady rain or snow for extended time
Weather warms when it passes

21. Occluded Front Occluded: When a cold front catches a warm front
Causes cloudiness and precipitation

22. Stationary Fronts Stationary: When a front is not moving
Causes cloudiness and precipitation
If stationary too long, flooding may occur

23. What happens if a stationary front remains in the same place for too long?
flooding