Jan 02, 2016
What Causes Wind?Air is a fluid – it moves easilyMovement of air caused by changing air pressureair pressure
Wind is movement of air from high pressure to low pressureigh pressure to low pressure
Air Movement
Types of Air MassesAn air mass forms when a large
amount of air stays in the same place over an area
Continental air masses form over land and are dry
Maritime air masses form over water and are moist
Polar air masses are coldTropical air masses are warm
Types of Air MassesThere 4 air masses affecting North
AmericacT- continental tropicalcP – continental polarmT – maritime tropicalmP – maritime polar
FrontsAir masses move and bump into
each otherFronts appear at the edges of two
air masses where they are colliding with each other
FrontsThere are 4 types of fronts:
Cold fronts Stationary frontsWarm fronts Occluded fronts
Cold frontOccurs when a cold air mass
overtakes a warm air massCold air forces warm air to rise
quicklyResulting in strong winds,
thunderstorms, and large amounts of precipitation
Cold fronts usually bring cooler weather, clearing skies, and a sharp change in wind direction.
http://www.suu.edu/faculty/colberg/hazards/weather/05_cnWfronts.html
Cold Front Diagrams
Warm FrontsOccurs 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 FrontWhen 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 frontWhen a warm air mass gets trapped between
two cold air massesStrong winds and heavy precipitation occur