Chp 20 - Weather Patterns and Severe Storms

Air Mass

Large bodies of air with similar temperatures and amounts of moisture at any given altitude

Source Region

Where air mass gets its characteristics

Polar Air Mass (P)

Forms in high latitudes

Tropical Air Mass (T)

Forms in low latitudes

Continental Air Mass (c)

Forms over land

Maritime Air Mass (m)

Forms over water

Maritime Tropical Air Mass

Warm air with lots of moisture

Maritime Polar Air Mass

Cold air with lots of moisutre

Continental Tropical Air Mass

Dry warm air

Continental Polar Air Mass

Dry cold air

Front

Place where two air masses meet

Warm Front

Warm air moves into a place that had cold air

Cold Front

Cold, dense air moving into a region with cold air

Stationary Front

Surface position of front does not move

Occluded Front

Active cold front overtakes a warm front

Thunderstorms

Storms which generate lightning and thunder

Lightning

An electrical discharge from clouds

Stepped Leader

Negative electricity towards ground

Return Stroke

Current back to cloud

Streamer

Positive charge moving up to clouds

Forked Lightning

Stepped leader branches

Heat Lightning

Distant lightning where you can't hear the thunder

Thunder

Sound of air expanding after lightning

Tornado

Violent windstorm that rotates and is called a vortex

Tornado Alley

Location in the Midwest where there is an increase in tornado activity

Enhanced Fujita Scale

How tornadoes are classified

Tornado Watch

Conditions are right for tornadoes to form

Tornado Warning

Tornado has been spotted

Hurricane

Spinning tropical cyclone with winds of at least 74 mph

Eye Wall

Circle of clouds in center of storm with greatest winds and heaviest rainfall

Eye

Center of a hurricane where winds calm and precipitation lessens

Storm Swell

Large waves caused from the hurricane

Storm Surge

High water levels (tide) caused from the hurricane

Microburst

Very fast descending air