1. Air Masses and Fronts
CHAPTER 17-1

2. FRONTS A FRONT is the boundary between two different air masses
Storms and changeable weather are common
Differences in air pressure, temperature and humidity are common with fronts
Four types of fronts are:
Cold
Warm
Stationary
Occluded

3. COLD FRONT A cold air mass replaces a warm air mass
Showers and Thunderstorms are common
Cooler and drier air follows the front

4. WARM FRONT A warm air mass replaces a cold air mass
Steady precipitation for several hours or days
Weather tends to be warm and humid

5. STATIONARY FRONT A front that does not move or barely moves
Two air masses in a “standoff” with neither one moving
Periods of rain, drizzle and fog are common
Several days of clouds and precipitation are likely
Temperatures remain constant and winds are gentle

6. OCCLUDED FRONT
Occurs when a warm air mass is caught between two cooler air masses
Warm air is “cut off” from the ground
Periods of rain or snow are common
warm
warm

7. FRONT SYMBOLS

8. WEATHER MAP SYMBOLS

9. ANTICYCLONES High pressure centers of dry air Usually called “HIGHS”
Appears as an “H” on a weather map
Winds spin clockwise in N. Hemisphere
Areas of sinking air in the center
Dry, clear weather is likely

10. ANTICYCLONES
HIGH PRESSURE AREAS

11. CYCLONES Low pressure areas Usually called “LOWS”
Appears as an “L” on a weather map
Winds spin counterclockwise in N. Hemisphere
Areas of warm, rising air in the center
Clouds and precipitation are likely

12. CYCLONES
LOW PRESSURE AREAS

13. REVIEW # 1
1) The air mass that forms over central Canada is called_________
2) The front that brings rising temperatures and steady rain is the ______front
3) The air mass that is warm and humid is
called__________
4) The front that brings showers and cooler
temperatures is called a ______front
5) The front that doesn’t move is called_______
6) An air mass that is warm and dry is called ?
7) Clear and dry weather is common to a _____

14. REVIEW # 2
What are the symbols used on a weather map for the four types of fronts?
In what direction do LOWS spin?
How many air masses are found in an OCCLUDED FRONT?
What are the weather conditions does a CYCLONE bring?
Air masses move across the U. S. from ________ to __________.
What kind of air mass is outside today?

15. REVIEW # 3 1) Maritime means ________________.
2) Tropical means________________.
3) Continental means_______________.
4) Polar means________________.
5) Several days of clouds and precipitation would be likely with a _________ front.
6) Which air mass forms over the Gulf of Mexico? ______
7) An “L” on a weather map is called ___.

16. REVIEW ANTICYCLONE 1) What direction does it spin in the northern
hemisphere? ______________
2) What kind of weather does it have? ________
___________.
3) What is another name for this feature?_______
_____________.

17. REVIEW CYCLONE 1) What direction does it spin in the northern
hemisphere? ___________________.
2) What kind of weather does it have?_________
______________.
3) What is another name for this feature?_______
__________________.