1. Air Masses and Fronts
Weather Patterns

2. What is an Air Mass?
An AIR MASS is a large body of air that takes on the TEMPERATURE and HUMIDITY (moisture) of a region
Usually THOUSANDS of miles in diameter
Forms over a source region with relatively stable conditions
Named for the SOURCE REGION (where it comes from)

3. Two Air Masses: each air mass has roughly the same temperature and humidity

4. Types of Air Masses: Named by where they come from!
POLAR: source region (colder air mass) (P)
TROPICAL: source region (warmer air mass) (T)
(basically north or south)
**************************************
MARITIME: Source region (formed over the ocean)(m)
CONTINENTAL: Source region (formed over land) (c)
(over ocean or land)

5. Types of Air Masses:
Maritime Tropical (mT): form over the tropical oceans, very humid
Maritime Polar (mP): form over cold ocean areas, cool but humid air
Continental Tropical (cT): Hot, dry , air masses from the southwest
Continental polar (cP): cool or cold dry air

6. Can you find the different continental air masses?

7. These circles enclose air masses.
What is the name of a line that surrounds an area of EQUAL TEMPERATURE? ISOTHERM

8. QUESTION:
WHICH AIR MASS DO YOU THINK WOULD PRESS DOWN ON THE EARTH MORE?
a COLD AIR MASS or a WARM Air MASS?
WHY?

9. How do the air masses move?
WINDS!
Uneven heating of the earth’s surface causes convection currents which cause differences in pressure, which causes winds.
Prevailing westerlies generally push the air masses from WEST EAST

10. FRONTS
Where Air Masses collide

11. What is a FRONT?
A weather FRONT forms when two unlike air masses meet (cold and warm air masses)
Because of the difference in TEMPERATURE and DENSITY of the air masses, the meeting results in storms and changing weather.
Fronts are named by which air mass is MOVING!

12. FOUR FRONTS COLD FRONT- cold air mass moving
WARM FRONT- warm air mass moving
STATIONARY FRONT – neither air mass moving
OCCLUDED FRONT-warm air mass caught between two cold air masses

13. COLD FRONT Colder, more dense air. Warmer, less dense air.
IF AIR MASS #1 MOVES TOWARDS AIR MASS #2  COLD FRONT
COLD FRONT SYMBOL:

14. COLDFRONT Colder, more dense air. Warmer, less dense air.
Cold Air moves in quickly to replace warmer air
Warmer air will rise, cool, then form large, CUMULONIMBUS CLOUDS (the thunderstorm kind)
Usually cause short lived, violent STORMS (rain, snowfall)

15. COLD FRONT DIAGRAM:
What happens to the temperature after a cold front moves though an area?

16. WARM FRONT Air Mass #1 Colder, More Dense Air Air Mass #2
Warmer, Less dense Air
IF AIR MASS #2 MOVES TOWARDS AIR MASS #1  WARM FRONT
WARM FRONT SYMBOL:

17. WARM FRONT Air Mass #1 Colder, More Dense Air Air Mass #2
Warmer, Less dense Air
WARM FRONT
Warm Air Mass moves in to replace colder air mass
Moves SLOWER than Cold front
Clouds that form are thinner (not puffy)
Usually causes LIGHTER, but LONGER periods of precipitation
In winter, brings snow.

18. WARM FRONT DIAGRAM: WARM AIR MASS collides with a cold air mass.
Warm air slowly moves OVER cold air. Longer rain storms.

19. STATIONARY FRONT Cold Air Mass Warm Air Mass
A COLD AIR MASS AND A WARM AIR MASS MEET, BUT NEITHER HAS THE FORCE TO MOVE THE OTHER
WARM FRONT SYMBOL:

20. Comparing Warm and Cold Fronts
Cold fronts move FASTER than warm fronts. The weather activity in a cold front is often VIOLENT and happens directly at the front. Cold fronts have sudden gusty winds high in the air creating turbulence. The weather activity in a warm front generally happens before the front passes.

21. SO WHY DO WE NEED TO KNOW ABOUT FRONTS????

22. BECAUSE FRONTS ARE WHERE THE STORMS ARE!!!!!!

28. HURRICANE

29. Locate the 4 types of fronts on this weather map.
Hint 1
Hint 2
Hint 3
Hint 4

30. Cold Fronts

31. Warm Front

32. Stationary Front

33. Occluded Front

34. Be a Weather Forecaster
You are planning to travel to Alabama in 2 days. The high temperature there for today is 68º F.
Use the map to help you predict whether the temperature in Alabama will increase, decrease, or stay the same. Explain why you think so.
Weather Fronts

35. Be a Weather Forecaster
There is a cold front approaching. The temperatures will probably be cooler behind the front.

36. Be a Weather Forecaster
Of course, meteorologists (weather forecasters) use much more data than fronts and air masses to help them forecast the weather more accurately. But any forecast is just a prediction of what might happen. Even with the best data, weather forecasts can be wrong.
MAP TAP
Weather Fronts