Environmental Science 102
Weather Systems: Fronts and Cyclones
Wind
Air moves from high pressure to low pressure.
Air will continue to move until the pressures are equal.
The greater the pressure gradient (i.e. the greater the difference between two location's pressures) the greater the force of wind.
Major Global Wind Belts
Polar Easterlies
Polar Front
Prevailing Westerlies
Subtropical High Pressure Belt
Trade Winds
Intertropical Convergence Zone (ITC)
Coriolis Effect
Apparent force which causes free moving objects to appear to be deflected from its path of motion.
Cause by the rotation of the Earth
Northern Hemisphere:
Southern Hemisphere:
Low Pressure Centers
High Pressure Centers
Anticyclones
Air Moves outward
Replaced by descending air
What happens to this air as it descends?
Cyclones
Air moves inward
Converging, rising air
What happens to this air as it rises?
Traveling Cyclones
Wave Cyclone - forms along the Polar Front in the mid- and high-latitudes.
Tropical Cyclones
Tornadoes
Fronts:
Cold Front
Cold air mass moving into a zone occupied by a warm air mass
Cold Front Diagram
Warm Front
Warm air mass moving into a zone occupied by a cold air mass
Summer:
Winter:
Warm Front Diagram
Occluded Front
Cold Front overtakes a Warm Front
Occluded Front Diagram Stage 1
Occluded Front Diagram Stage 2
Dry Line
Dry air (cT) converges with moist air (mT).
Dry Line Diagram
Formation of a Wave Cyclone
Two large anticyclones from along the Polar Front
A low pressure trough develops between them where the winds converge.
Stationary Front forms
Low Pressure center develops.
Rotation causes the Cold Front to begin to move around the low pressure.
Cold Front overtakes the Warm Front.
Occluded Front forms.
Occluded Front breaks down.
Cyclonic Motion
Storm Tracks