What causes a Tornado?

The first step to a tornado is a thunderstorm. The storm starts when warm , humid air rises out of the ground. When they cool in the upper atmosphere it makes clouds. The water droplets start to fall, making a down draft which meets with the updraft. That keep on giving humid air to the thunder cloud. The most violent time in the storm is now. The Tornado forms in the midle of the downdraft and the updraft. The updraft sucks away the air from the ground."Air rushes in to take it's place. The water drops push into the dowmdraft". Thats what forms the funnel-shaped cloud. when the funnel picks up dirt it makes the funnel darker.