Movement of Air Air Masses Winds Air Masses

Movement of Air – Air Masses & Winds

Air Masses Air Mass = large body of air that takes on characteristics of the area over which it formed Conditions: Over land = dry Over water = wet Polar regions = cold Tropical regions = warm

Air Masses Types of Air Masses: Continental polar (c. P) – cold, dry Continental tropical (c. T) – warm, dry Maritime polar (m. P) – cold, wet Maritime tropical (m. T) – warm, wet Equatorial – hot

Winds When air is heated: Its density decreases Warm air rises, produces an area of low pressure Cooler denser air produces an area of high pressure, and moves in under rising air

Local winds Sea breeze –during the day solar radiation warms the land more than water air moves inland from the ocean due to air over land heating up quicker (and is less dense than the ocean air) Land breeze –at night when cool air from land flows seaward air moves toward the ocean as the land air cools quicker

Land Sea Breezes

Fronts Air masses move and bump into each other Fronts appear at the edges of two air masses where they are colliding with each other

Fronts There are 4 types of fronts: Cold fronts Warm fronts Stationary fronts Occluded fronts

Cold front Occurs when a cold air mass overtakes a warm air mass Cold air forces warm air to rise quickly Resulting in strong winds, thunderstorms, and large amounts of precipitation

Cold fronts usually bring cooler weather, clearing skies, and a sharp change in wind direction.

Cold Front

Cold Front Diagrams

Warm Fronts Occurs when a warm air mass overtakes a cold air mass Warm air slowly rises over the cold air Starts with steady rain (8 -12 hours) but eventually clears when temperatures rise Warm fronts tend to move slowly are far less violent then cold fronts

After warm front passes, weather becomes warm and humid, but generally clear

Warm Front

Warm Front Diagrams

Stationary Front When neither air mass can move the other Similar to warm fronts and can remain in same place days Light wind and precipitation occur across entire region affected

Occluded front When a warm air mass gets trapped between two cold air masses Strong winds and heavy precipitation occur