There are many different kinds of tornadoes. They can be narrow, cylindrical, cone or wedged in shape.
A supercell tornado is the offspring of a supercell thunderstorm. These storms have a continuous updraft of air which also rotates. These produce the wedged-shaped tornadoes that remain on the ground for the longest amount of time, at time more than an hour. Supercell tornadoes can also produce winds greater than 200 miles per hour. These are most often seen in the center of the United States.
Dust devils occur on clear days which are hot and dry. They usually form in the late morning or early afternoon. They are generally brought about by light desert breezes which create a rotating cloud of dust. They can have speeds of over 20 miles per hour. Dust devils do not have a long life cycle; however, there have been some that have lasted several hours. These are usually harmless causing some damage in the southwestern section of the United States. Dust devils are also known as dancing dervish, desert devil or sand devil.
Landspouts are not as strong as a supercell. They can form under a cumulonimbus or towering cumulus cloud. Landspouts form, usually, along the front of a downdraft that has been cooled by the rain from a thunderstorm.
When there are major forest fires or volcanic eruptions, a firewhirl can form from the heat created. This rotates like a tornado, but is a cloud of smoke and/or fire. The winds can exceed speeds of 100 miles per hour. These are formed when the heat or fire updraft creates a week whirl or eddy in the wind. They are also known as fire tornadoes, fire devils or firenadoes.
A gustnado is a weak, short-lived tornado that looks like a debris cloud or dust devils. They do not have to have a connection to clouds.
When a tornado appears over water, it is considered to be a waterspout. Some can come from a supercell thunderstorm, but most are from weak thunderstorms or cumulus clouds that grow quickly. These are not usually very intense and very little damage is caused by them. At fifty yards wide, these are not considered to be very large. They form over warm tropical oceans, even though the funnel itself is created from freshwater from condensation. When they reach the land waterspouts usually disappear.
Rope tornadoes are common tornadoes and get their names from their rope-like shape. The distance from the base to the top may be very long and the funnel may form an S-shape. Even though these tornadoes travel along a narrow path, the damage they inflict can be massive.
No matter which type of tornado may appear, it is best to take safety precautions when one may be traveling your way.