1. Fronts

2. Front-the area where 2 air masses of different densities meet
*Air masses that form from different areas often do not mix because of having different densities.
There are 4 kinds of fronts:
Cold front
Warm front
Occluded front
Stationary front

3. Cold Front Cold air mass replaces a warm air mass
Cold air moves under the warm air because cold air is more dense
Move in quickly
Creates thunderstorms, heavy rain, or snow
Cooler weather results from this b/c air is cooler and drier than the air mass its replacing

4. Warm air moves over cold air
Warm Front
Warm air moves over cold air
GRADUALLY replaces the cold air (colder air is harder to push b/c it’s denser)
Warm fronts usually bring in drizzly rain and followed by clear and warm weather.

5. Occluded Front Warm air mass is caught between two colder air masses
Cold air mass moves under (b/c it’s denser) and pushes warm air up
Sometimes the two colder masses mix and causes:
Cool temps
Large amounts of rain
Snow

6. Stationary Front Occurs when warm air mass meets a cold air mass
Neither air masses have enough force to lift the warm air mass over the cold air mass
The cold air mass and warm air mass remain separated (usually b/c there’s not enough wind to push them against each other)
This brings MANY days of cloudy, wet weather

7. Fronts
Draw a picture of each front:

8. Air Pressure and Weather
Areas of different pressure affect weather

9. Cyclones and Anticyclones
is an area in the atmosphere that has lower pressure than surrounding areas.
Winds spiral toward the CENTER.
Air masses converge and rise.
Anticyclone
is the rotation of air around a HIGH pressure center
rotates in the direction OPPOSITE of the Earth’s rotation (clockwise).
Anticyclones can form cyclones

10. How do cyclones and anticyclones affect weather?
Air in center rises
Air sinks
Cools and forms clouds/rain
Warms and absorbs moisture
Rising air brings stormy weather
*Tracking cyclones and anticyclones help meteorologists predict weather.
Sinking air brings dry, clear weather