IF you look up in science books of tornados there are some intresting fact
think of it like this
the earth has a lot of energy it needs to get rid of
so when a tornado is formed the earth creats that and get rid of it energy through the tornado
if there was no tornados then the earth could get rid of it energy another way
like a thunder storm destroying a state or if it builds up so much it could wipe out a country if the tornado does not get rid of its mas production of its energy