A tornado is a violent funnel of wind in contact with the ground that extends from or is below a cumuliform cloud which may take on the appearance of a funnel cloud. Tornado wind speed can reach 318 mph. The only continent in which tornadoes have not been reported is Antarctica. How is a tornado created?
Tornadoes form when warm, wet air collides with cool, dry air. The warm air is pushed upward. This does not automatically form a tornado. In fact, this is a common condition causing the development of thunderstorms, but not all thunderstorms yield tornadoes.
Water vapor condensation that accumulates in the cloud produces energy. Increases in energy can cause the air temperature to rise in the updraft. This also increases the energy of the upward moving and downward moving air currents.
The wind may form a mesocyclone. About half of the mesocyclones that form will turn into tornadoes. A mesocyclone is essentially a rotation of air. The wind of a tornado almost always rotates in a clockwise direction, but tornadoes can also have a counter-clockwise rotation.
Tornadoes are rated on the Fujita scale (F-scale). F-0 and F-1 tornadoes do the least amount of damage. F-2 tornadoes can tear roofs from houses. An F-5 tornado has wind speeds in excess of 300 mph and causes the most damage. The wind speed and category of the tornado is often estimated by the type of damage that it caused. While an F1 tornado may knock a mobile home from its foundation or flip cars, an F4 tornado can throw cars and raze houses.
There is more than one form of tornado. A supercell tornado develops from a supercell thunderstorm that produces a strong, rotating updraft of air. These supercell thunderstorms often produce hail. Tornadoes from these supercell thunderstorms can be the most destructive form.
A gustnado is a weak, dust whirl that may form along the gust front of a thunderstorm. A tornado that forms over warm, tropical water is called a waterspout. Waterspouts are weak tornadoes that form with the condensation from the warm water. A landspout is a weak tornado similar to a waterspout except landspouts form over land.
Tornadoes may have more than one vortex. Tornadoes can have many vortices that rotate around the center of the tornado. If the vortex of the thundercloud is disturbed, the tornado may hop and reform. Therefore, a tornado may appear to hop, or briefly dissipate before resuming its path.