A tornado was a weather phenomenon where a large and incredibly turbulent rotating funnel of air formed from clouds in the sky.
The people of Bellus created a tornado to attack a city on Demeter. The First Doctor used a tremulator to divert the energy causing it back to Bellus. (COMIC: The Ordeals of Demeter)
Professor Brian Phipps' house was destroyed by what appeared to be a freak tornado, but which turned out to be a conduit to an alien spaceship above Earth. (COMIC: The Vortex)
In 2050, the Royal Albert Hall and Hyde Park were destroyed by a tornado caused by an Aeolian. (TV: Aeolian)