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:
- warm, moist air moving up from the Gulf of Mexico
- cold, dry air moving down from Canada or out from the Rocky Mountains
- 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