Air Masses large bodies of air characterized by a similarity of temperature and moisture.
Air Mass Weather - fairly constant weather over several days caused by the apssing of an air mass.
Front - the boundary between two air masses
Source Regions - Polar (P) and Tropical (T) / continental(c) and maritime (m)
cP: dry and cold
mP: wet and cold
cT: dry and warm
mT: wet and warm
Fronts are boundaries that separate different air masses. No matter which air mass is advancing warm air lifts over cool air.
Warm Front - gradual gradient, light widespread precipitation
Cold Front - blunt, heavy precipitation
Middle-latitude cyclones should not be confused with hurricanes. The word cyclone is used by meteorologists to indicate a low pressure system of rotating winds. The surface air that feeds a cyclone originates as air flowing out of an anticyclone.
Caused by vertical motion of warm, unstable air. These storms are associated with cumulonimbus clouds. Thunderstorms include heavy rain, lightning and occasionally hail.
In the United States, thunderstorms typically form within warm, humid (mT) air masses that originate over the Gulf of Mexico.
The most severe thunderstorms in middle latitudes form along or ahead of cold fronts. Forceful lifting of unstable mT air masses trigger thunderstorm development.
Updraft: a surge of warm air.
Downdraft: downward movement of air.
The life span of a cumulonimbus cell within a thunderstorm complex is only about one hour. Many cells are generated during a thunderstorm.
A tornado is a local storm of short duration that is very destructive.
A tornado is a violent wind storm that takes the form of a rotating column of air that extends downward from a cumulonimbus cloud.
The F-scale is used to rank tornadoes based on wind speed; F0 to F5
Tornado Watch conditions exist for tornado formation
Tornado Warning a funnel cloud has been sighted
Doppler Radar detects the formation and developments of mesocyclones (mid-latitude cyclones) rotaing winds that precede tornado formations
Hurricanes are the greatest storms on Earth. They form in almost all tropical waters between 5o and 20o latitude.
They are known as typhoons, cyclones, hurricanes depending on where they form.
The doughnut-shaped wall of intense convective activity surrounding the center of the storm is called the eyewall
Eye - center of the storm, cloudless and calm
Hurricanes develop over ocean water with temperatures of at least 80o F. Hurricanes do not form within 5o of the equator because the Coriolis effect is too weak to start rotary motion.
Tropical Depression wind speeds up to 38 mph
Tropical Storm wind speeds between 38 mph and 74 mph
Hurricanes diminish in intensity when:
Hurricanes are placed into categories 1 to 4 based on wind speeds.
Damage from Hurricanes results from:
Storm Surge - a dome of water that sweeps across the coast near the point where the eye makes landfall