What is a tornado and how do they form?

Answer 1

A tornado is a violently rotating and destructive column of air extending from the base of a thunderstorm to the ground.

The formation of tornadoes these is complicated.

First, a condition called wind shear, in which the speed or direction of the wind changes with altitude. If the shear is strong enough it can essentially tilt a thunderstorm, this separates the updraft and downdraft of the thunderstorm, preventing them from interfering with one another. This allows the storm to become stronger and last longer.

Additionally, if the wind shear is strong enough it can start the air rolling in what is called horizontal vorticity. This horizontal vorticity can then be turned vertical by a thunderstorm's updraft. When this happens, the thunderstorm may start rotating. The rotation is especially strong in an updraft called a mesocyclone. If the storm intensifies rapidly enough, a relatively warm downdraft called a rear-flank downdraft or RFD can wrap around the bottom part of the mesocyclone. This can then tighten and intensify its rotation and bring it down to the ground to produce a tornado.

Answer 2

A tornado is a rapidly rotating column of air extending between a thunderstorm and the ground. They form from strong thunderstorms when warm, moist air near the surface converges with cool, dry air aloft, creating an unstable atmosphere that can lead to the development of rotating updrafts.