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Tornado Facts By Scott Stanko Defined as a rapidly rotating column of air ranging in width from a few feet to more than a mile wide and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud. The word tornado comes from the Spanish word for thunderstorm tronada, this in turn was taken from the Latin "tonare" which means "to thunder" eventually it was turned into "ternado" by English sailors in the 1500's to mean a "violent tropical storm" and eventually changed by Americans to the word as we know it today "Tornado". But what are some of the other interesting tornado facts that you never really hear about. I thought I would list some that I have found from the research that I have done. A tornado reaches its greatest power as the funnel reaches its greatest width, then it starts to shrink and become more tilted as it loses power until it becomes ropelike and starts to dissipate or decay as they call it. There are five atmospheric conditions that prime the atmosphere for tornadic activity. 1) a surfaced based layer at least 3000 feet deep, of warm moist air, overlain by dry air at midlevel's; 2) an inversion separating the two layers, preventing deep convection until the potential for overturning is established causing a horizontal spinning in the atmosphere; 3) a rapid decrease in air temperature with height above the inversion; 4) A lifting of the air mass by a front or upper level disturbance; 5) an updraft rising up into the storm from the lifting of air mass, these updrafts tilt the spinning in the atmosphere to a vertical position which is where the funnel will usually appear. In the United States the average tornadoes are around 500 feet in diameter, and stay on the ground for an average of 5 miles. However there is very wide range of tornado sizes. They are rated by a system called the Fujita Scale or "F- Scale". The F-Scale was devised in 1951 by the Japanese-American meteorologist Tetsuya Fujita. It classifies tornadoes on a hierarchy which is listed below: F0-Winds of (40-72) mph. F1-Winds of (73-112) mph. F2-Winds of (113-157) mph. F3-Winds of (158-206) mph. F4-Winds of (207-260) mph. F5-Winds of (261-318) mph. The United States has the most tornadoes of any country, averaging about 1200 per year. Four times more than all of Europe. This is due mostly to the unique geography of the continent. It is a large continent extending from the tropical south all the way into the arctic areas, and has no major east-west mountain range to block air flow between these two areas. In the middle latitudes known as "tornado alley" where most of the world's tornadoes occur, the Rocky Mountains block moisture and atmospheric flow, allowing drier air downstream to the east of the mountains. The desert areas in the Southwest also feed drier air into this area while the "Gulf of Mexico" feeds abundant low level moisture. This topography sets the stage for many cold and warm air collisions which breeds strong storms with lots of moist air for fuel. The appearance of a tornado can be affected greatly by the lighting conditions at the time. A tornado which is "back-lit" with the sun behind it will appear very dark; while the same tornado viewed with the sun shining towards it from behind the viewers back may appear gray or white. Debris can also affect the color of a tornado, when dust or debris is sucked up into the funnel it can appear darker. This can be seen in many pictures of tornadoes. Tornadoes are most common in the spring and least common in the winter. Since spring and fall are transitional periods (warm to cool and cool to warm) there are more chances of cooler air colliding with warmer air resulting in thunderstorms. But on rare occasions favorable conditions for tornadoes can occur at time of the year. Worldwide most tornadoes occur in the late afternoon between 3pm and 7pm. After these times the air starts to cool down as the sun lowers, however tornadoes can occur any time of day or night if favorable conditions present themselves in the atmosphere. The most extreme tornado ever recorded was the "tri state tornado" which hit parts of Missouri, Illinois and Indiana on March 8th 1925. Although tornadoes were not ranked at all during that time period it was likely an F5. Its path was 219 miles long, lasted for about 3.5 hours, and was moving at a speed of an estimated 73 mph. There are many myths about tornadoes one of them is that if you open the windows in your house you will lessen the damage caused by the tornado. This is untrue there is some research that opening the windows may increase the severity of the damage caused by a tornado. A tornado can destroy a house whether the windows are open or closed. Another myth is that if you sit in the southwest corner of the basement you are safer, again this is untrue the safest place is in an underground room on the side or in the corner opposite the tornadoes approach. Many people build a safe room for safety in their basements which should include a weather radio, flashlights, water, first aid kit, and some non perishable food. I really hope you enjoyed these tornado facts. The study of weather and the atmosphere is a relatively young science and tornadoes even more so. Although studied for about 140 years there are still aspects of the tornado that remain a mystery. That may be why so many people are fascinated with this awesome force of nature. This author is an novis storm chaser and has created a blog with interesting tornado facts and pictures of tornadoes that he has captured. You can view them at http://www.tornadofactsblog.com
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