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Weather Systems Vocabulary

Weather Systems Vocabulary. Air mass – huge body of air with the same temperature and moisture characteristics Front – a boundary between two air masses Hurricane – a tropical cyclone of low pressure and very strong winds

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Weather Systems Vocabulary

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  1. Weather Systems Vocabulary • Air mass – huge body of air with the same temperature and moisture characteristics • Front – a boundary between two air masses • Hurricane – a tropical cyclone of low pressure and very strong winds • Thunderstorm – Cumulonimbus cloud possessing thunder and lightning, usually accompanied by strong winds, rain and sometimes hail • Tornado _ whirling funnel of air of very low pressure and very strong winds; must touch the ground to be called a tornado

  2. Air Masses • Usually 1,000 miles across or more • Has the same temperature and moisture characteristics • When it travels out of its area it carries the characteristics (front from Alaska will be cold and dry) • Usually from a Tropical or polar region • They are classified by their source region, such as (P) Polar, (A) artic, (T) tropical and (E) equatorial

  3. FRONTS • They are classified as warm, cold, stationary or occluded. • When warm air moves in this is a warm front • When cooler (cold) air moves in this is a cold front • When two air masses bump into each other and neither moves it is called stationary. • An occluded front is when three air masses meet. • Cold fronts are indicated in blue, warm fronts in red

  4. Severe weather • There are three main weather phenomena • Thunderstorms • Tornadoes • hurricanes • All three are associated with cumulonimbus clouds • All three are potentially deadly

  5. Thunderstorms • Come from cumulonimbus clouds and always have thunder and lightning • Lightning is a flash of light produced by electrical discharges in a thunderstorm. It discharges millions of volts and heats the air to 60,000 degrees F. • Thunder is the sound sent out by rapidly expanding gases along the lightning's trail • They usually contain heavy rain, strong winds and sometimes hail • Hail is small balls of ice

  6. Thunderstorm stages • They have three stages: building, mature, and dissipating • Building stage has updrafts as the storm builds and grows vertically. • Mature stage the moisture that is carried up gets heavier and starts to fall, this creates downdrafts… there are still updrafts so the moisture moves up and down several times • Dissipating, contains only downdrafts (the storm is blowing itself out) • In the US alone 200 people are killed by lightning each year and 400-500 are injured.

  7. Safety rules for thunder and lightening • Stay away from windows and doors • Don’t use electrical appliances • Don’t use the phone or take a shower or bath • If outside, go inside if possible • Move away from water such as pools, lakes and the ocean • If you are in a boat, go ashore • Stay away from metal objects like gold clubs, fishing poles, bicycles, farm equipment or motorcycles • Don’t stand in an open field, a hilltop or golf course, stay low by sitting. • Don’t stand under a single tree (if you must be under a tree, look for a group of trees of similar height) • If in a group of people, stay low and spread out • If in a car, stay there.

  8. How do thunderstorms affect aviation? • Cumulonimbus clouds mean the air is unstable • Thunderstorms have violent up and down drafts • Unstable air causes turbulence which raises havoc with planes • Hail can do serious damage to airplanes • Lightning can cause electrical devices on the plane to go out or even shut down engines • Pilots usually fly above or around thunderstorms

  9. Tornadoes

  10. Tornadoes • Destructive and devastating to life, property and nature • Occur in every month of the year • About 700 annually in the US • Unstable air of low pressure • Most are counter-clockwise • Air is sucked into the center (vortex) of the storm • The funnel of a tornado appears dark because of the dirt and debris it picks up

  11. Tornado winds • They can be stronger than 261 mph • They can be as big as 500 yards (5 football fields) across • They are measured on the Fujita wind damage scale • F-0 light up to 72 mph • F-1 moderate 72 to 112mph • F-2 considerable 113 to 157 mph • F-3 severe 158 to 206 mph • F-4 devastating 207 to 260 mph • F-5 incredible above 261mph

  12. HURRICANES • Produce many thunderstorms and tornadoes within them • Their winds are not as strong as tornadoes usually but still devastating • Affect hundred of miles wide • Flood coastal cities and dump many inches of rain • The eye of the hurricane can be 15 miles wide! • Before storms become hurricanes they are first tropical depressions then tropical storms • Judged on the saffir-simpson scale • Cat 1 • Cat 2 • Cat 3 • Cat 4 • Cat 5

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