A tornado is “the smallest of storms, usually no more than twelve hundred feet wide, and generally travelling only 16 miles before they die.” But these are no baby storms. They are sudden, swift and deadly. They often cause more life loss than hurricanes. “Damage when a tornado strikes is instantaneous and often complete. ” They even make houses
“In many respects a tornado is the big brother of the whirl set up in a bathtub when you pull out the drain and the water all flows down.” In the bathtub whirlpool, water gets fulled down by the force of gravity. But it cannot simply go straight down, because the air pressure inside the drain is too great. So turbulence develops around the surface. once the water starts rotating, centrifugal force opens up a gap in the water, allowing the air to escape. Tornadoes form in a similar way, but instead of being pulled downwards by gravity, they are controlled by giant updrafts. Tornadoes are also grouped with other whirlwinds, including waterspouts, dust devils, and hurricanes.
A tornado is usually formed on the verge of a cold front. Usually when cold air masses run into air masses, they force their way under it, since cold air is heavier than warm air. But in rare cases the cold air mass will roll over the warm air mass. This “tongue” of cold air is the cause of most tornadoes. Warm air will start floating into the tongue of cold air and cool, forming clouds. “When the cloud develops, the tongue of cold air can be seen as the funnel cloud that marks the beginning of a tornado.”When warm air next to the funnel gets sucked in, the air next to that takes its place. This means that the funnel drops down and sucks up dust, becoming a mature tornado.
“Tornadoes begin when a funnel-shaped cloud forms high in the air and roars down to the ground.” The cloud is usually more or less vertical, generally retains a thickness throughout, and is somewhat whiter than the thunder clouds around it, at least at the top. There are common execptions however. Some tornadoes go horizontal so much as a half mile. Some suck up so much dust they are completely black. Some are wedge or rope-shaped. Some are even invisible.
A tornado will usually travel southwest to northeast for 15-20 miles and then dissapate. The path can be anywhere from 100 feet to several miles across. On rare instances the tornado can make a U-turn or even go in circles. They can also “drop down, strike a single point, and then dissapate.”
I have always been fascinated by tornadoes. Well, at least after I turned 6. Before that I always had crazy dreams about them, and whenever a storm passed, I would look at a piece of cloud and say, “Daddy, is that a tornado?” I hope you have enjoyed my essay on them as much as I did.
Irving, Robert. Hurricanes and Twisters. Alfred A. Knoff, 1955
Tornadoes of the United states. Norman, Oklahoma: University of Oklahoma Press, 1953