Fronts

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

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

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.

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

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

Fronts Draw a picture of each front:

Air Pressure and Weather Areas of different pressure affect weather

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

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