FRONTS

24-2

Fronts

When 2 air masses meet density differences keep them separate

Front- boundary between air masses

100’s to 1,000’s of miles wide

Cold Front

Cold air mass overtakes a warm air mass

Cold air lift warm air up

Short lived

Violent

Squall line – long line of heavy thunderstorms

Warm Front

Front edge of an advancing warm air mass

Cold mass retreats from an area

Precipitation over a large area

Stationary Front

Fronts either move very slow or don’t move

Occluded Front

Cold air mass overtakes warm air mass

Lift warm air up above

Polar Front

Cold polar air meets warm tropical air

Midlatitude Cyclone

Low pressure

Rotating wind

Moves towards the rising air of central low pressure regions

Midlatitude Cyclone Stages

Anticyclone

Air sinks and flows outward from a center of high pressure

Clockwise in NH

Dry weather

Thunderstorms

Heavy storm with rain, thunder, lightning, and winds

3 stages:1. Cumulus – warm moist air rises

2. Mature – dark cumulonimbus (heavy rain)

3. Dissipating - end

Lightning

Clouds discharge electricity

Rapid expansion of air – thunder

Lightning fun facts!

Hurricanes

Tropical oceans

120 mph winds in a spiral

Intense low pressure

Winds increase towards the center – eye

Eye – calm sinking air

Storms surge – rising sea level

Safir-Simpson Scale

Tornadoes

Rotating column of air

High winds

Funnel-shaped

400 km/hr

Thunderstorm meets a high altitude horizontal wind

Tornado Alley