A tornado is a mobile, destructive vortex of violently rotating winds having the appearance of a funnel-shaped cloud and advancing beneath a large storm system.
They are formed by moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere. the impact of the tornado can destroy mostly anything and destroy a town very fast. the fastest wind speed in a tornado is 110 MPH. And the lowest wind speed to form a tornado is 45 MPH.
In 1930 a tornado's hit Bynum, Irene, Mertens, Hill County; Ennis, Ellis County; Frost, and Navarro County there was 22 deaths and 72 injured 2,100,000 $ in costs.
This is some footage of what a tornado can do
Humans prepare for tornadoes by listening for watches or warnings or they go turn on a TV and watch the news. Or you could could into your downstairs somewhere not close to windows or big things (chairs,weights,tables,ect,)