A force, such as friction, that operates opposite the direction of motion of a body and tends to prevent or slow down the body's motion. A measure of the degree to which a substance impedes the flow of electric current induced by a voltage. Resistance is measured in ohms.
What is a tornado? A tornado is a violent rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of up to 300 mph. They can destroy large buildings, uproot trees and hurl vehicles hundreds of yards. They can also drive straw into trees.
Home > Hurricanes & Society > Hurricane Hazards and Impacts > Tornadoes. Tornadoes. A tornado is a violently rotating column of air that extends from the bottom of a cumuliform cloud, such as a thunderstorm, to the ground. Tornadoes are often (but not always) visible as a funnel cloud. It is important to never confuse a tornado with a hurricane or other tropical cyclone because tornadoes and hurricanes are very different phenomena.