|.: Formations of Natural Catastrophes :.|
Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height, creating an invisible, horizontal spinning effect in the lower atmosphere. Warm rising within the thunderstorm updraft tilts the rotating funnel of air from horizontal to vertical. An area of vertical rotation, ranging from 3-9.5 kilometres (2-5 miles) wide, extends through most of the storm. Progressively, with increasingly warm air and a constant updraft, a tornado forms within this area of rapid rotation.