Tornadoes are cyclonic winds that rotate at very high speeds
around a low pressure center. Tornadoes often occur in mid-
western states of Texas, Missouri, Oklahoma and Kansas. This
area has been termed tornado alley due the high frequency at
which tornadoes occur. The reason these four states are so
prone to tornadoes is due to the prime conditions which exist
in this region.
A tornado develops as warm air from the Gulf of Mexico
travels north and collides with cold air coming over the
Rocky Mountains. With this collision thunderstorms develop,
and as the warm air continually rises and the cold air
descends, a path of circular turbulence develops. Of course
this occurs in all thunderstorms, but there is one final
ingredient that causes these storms to be tornadic. The Jet
stream, which are high winds that located high in the
atmosphere, takes the circular turbulence of the thunderstorm
and turns it into a vertical rotating column of air. When the
cylinder emerges from the storm, and develops in intensity
around a low pressure core, a Tornado has formed. This lower
pressure core also cools the water vapor with in the vortex
which gives tornadoes there cone-like appearance. No matter
whether the tornado, touches the ground or begins to emerge
from the cloud bank and stalls and returns in to the cloud,
it is still consider a tornado.
Tornadoes are usually accompanied by hail because of the
circular turbulence of the water droplets being carried up
into the atmosphere where it freezes. However, hail does not
have to exist before a tornado will form.
Tornadoes usually only last a few minutes but can last up to
an hour or more depending on its intensity. Size of tornadoes
can range from 100 feet to 1.5 miles. Wind speed is
typically around 110 mph can reach up to 320 mph. Tornado
ground speed ranges from 20 - 50 mph but can go as fast as 70
mph. Typically tornadoes in the northern hemisphere travel
southwest to northeast, spinning counter-clockwise.