Tornadoes and Formation

Tornadoes

• spanish “tornar” = to turn
• rapidly rotating column of air from a large thunderstorm
• fastest wind speeds on earth
  • move at 62 mph
  • rotate at up to 310 mph
  • 1% of tornadoes have wind speeds of >200 mph, but they account for >70% of tornado deaths
• more intense than the largest hurricanes, but they affect a smaller area

Tornado Formation

• 70% of tornadoes occur in central US

• low-lying topography

  • no mountain ranges to disrupt flow of air masses

• meeting of air masses creates ideal conditions for thunderstorm formation:

  1. warm, moist air moving up from the Gulf of Mexico
  2. cold, dry air moving down from Canada or out from the Rocky Mountains
  3. high altitude jet stream moving east of >150 mph

• all 3 masses are moving in different directions

• when they collide, wind-shear can happen

  • thundercloud starts spinning

• warm, moist air rises, latent heat then releases, and strong updrafts are then created, updrafts sheared and spun by fast-moving cool air and jet stream

• spinning motion enhanced by updrafts and downdrafts

Tornado Alley

• meeting of cold and warm air masses forces warm air to rise
• tornadoes usually head northeast following the jetstream
• mostly flat so there is no obstacles to slow or stop the winds
• tornadoes are most common during the late spring and early summer

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