Weather Disturbances

What is a weather disturbance?•Depressions (lows), tropical storms….

•Typhoons, hurricanes….

•Thunderstorms, tornados….

Mid-Latitude Depression•Polar front + tropical front

•Start off with a stationary front

Mid-Latitude Depression•Westerlies push front into counter-clockwise rotation

•At the end, occluded front occurs

Mid-Latitude Depression•Significant amounts of rain

•In winter, can cause snowstorms or freezing rain

Thunderstorm/Hailstorm•Warm, moist air forced upward

•Severe updrafts and downdrafts within cumulonimbus

Thunderstorm/Hailstorm•Water droplets caught in circulation can turn into hail

Thunderstorm/Hailstorm•Lightning – discharge of electricity

•Thunder – lightning superheats air around it, produced a shockwave

Hurricanes•North America: hurricanes

•Indian Ocean: Cyclones

•China Sea: Typhoons

Hurricanes•Distinctive eye feature (15-50km wide)

Hurricanes•Require warm air and large body of warm water to develop

Hurricanes•Strong winds can pile seawater in a storm surge

•Moves slowly, lasts for days

Hurricanes•Given names to prevent confusion

•Started in 1953, 6 lists of alphabetical names

•Only time a change made to list is when hurricane is particularly destructive

Tornados•Most violent

•Winds +500km/hr

Tornados•Very low air pressure

•Often generated where polar air meets maritime tropical

•Often has hail, rain, lightning