Geography 488 Thematic Cartography & GIS Teressa Keenan Master of Library and Information Science (d-MLIS) Dimmitt, Texas. NOAA Photo Library

May 2, 2006Geog From Points to Polygons & Beyond: Mapping the Historical Record Tornadoes F-Scale Physical Damage Tennessee Tornado Trivia Union City OK 1973.NOAA Photo Library,

May 2, 2006Geog Characteristics of Tornadoes Violent Windstorm Twisting Funnel Shaped Cloud Cool air overrides a layer of warm air Derived from Spanish verb “tomar” = to turn Lakeview, Texas in NOAA Photo Library, NOAA Central Library

May 2, 2006Geog White Deer, Texas, USA. Photo by Jimmy Deguara and David Croan Test Your Twister IQ? Tornadoes can rotate clockwise as well as anti-clockwise. Tornadoes cause houses to explode from changes in air pressure. The best place to be during a tornado is generally in the southwest corner of the basement. TRUE! Most in the US spin counter- clockwise. Some spin clockwise & a few have been seen to change from anticyclonic to cyclonic! False! Homes are damaged by strong winds & flying debris not air pressure changes. False! C urrent advice is to move to a protected interior room on the lowest floor of the building.

May 2, 2006Geog Fujita Scale Tetsuya (Ted) Fujita ( ) Introduced in 1971 Accepted by National Weather Service 1973 Allen Pearson –Path length & width Measures Intensity –Empirically derived from structural damage –Directly derived with high resolution Doppler radar wind speed data Enhanced F-Scale Feb. 1, 2007 Near Seymour, Texas in Photographer: D. Burgess NOAA Photo Library

May 2, 2006Geog Tornado in Attica, Kansas, USA. Photo by Jimmy Deguara F-Scale continued Rank intensity based on damage Contrived by connecting Beaufort wind scale with the speed of sound in 12 steps. Estimated strength of wind based on observed damage Fujita, T.T Tornadoes and downbursts in the context of generalized planetary scales. J. Atmos. Sci, 38,

May 2, 2006Geog F-0: Light Damage (40-72 mph) roof shingles, tree branches etc. F-1: Moderate Damage ( mph) overturn mobile homes, cars etc. F-2: Significant Damage ( mph) demolish mobile homes, tear off roofs, large trees uprooted, light objects become missiles.

May 2, 2006Geog F-3: Severe Damage ( mph) roof & walls of frame houses, trains overturned, most trees uprooted. F-4: Devastating ( mph) homes leveled, blown off foundations, large missiles generated. F-5: Incredible Damage ( mph) trees debarked, steel reinforced concrete structures damaged, cars become missiles

May 2, 2006Geog Union City OK 1973 NOAA Photo Library, NOAA Central Library Fujita - Table

May 2, 2006Geog

May 2, 2006Geog

May 2, 2006Geog Sharon, Kansas, USA. Photo by Jimmy Deguara of Tennessee Tornado Trivia Is ranked 23 rd for frequency Ranks 9 th in the US for number of deaths, Ranked 11 th for injuries And 25 th for cost of damages Effgen, C. (n.d.). Tennessee tornadoes. Retrieved April 26, 2006, from

Union City OK 1973 NOAA Photo Library, NOAA Central Library When compared to other states by the frequency per square mile, Tennessee ranks: 23 rd for the frequency 6 th for fatalities 9 th for injuries per area and 26 th for costs per area

28 tornadoes lashed 19 counties of Middle and Eastern Tennessee between the early afternoon of April 3 and 1:00 a.m. the following morning-in the worst single outbreak of tornadoes in the State's history. The storms left 50 people dead, 635 injured, and caused approximately $30 million damage. It was the worst tornado outbreak in U.S. history with 148 twisters touching down in 13 states. Before it was over 16 hours later, 330 people were dead and 5,484 were injured in a damage path covering more than 2,500 miles. Carey, C. (1974). Details of outbreak by state: Tennessee. In NOAA and the 1974 tornado outbreak. Retrieved April 26, 2006, from National Oceanic and Atmospheric Administration Web site:

May 2, 2006Geog Twister IQ – part 2 By opening the windows, you can balance the pressure inside and outside your home so a tornado will not do damage. A tornado is always accompanied or preceded by a funnel cloud. When traveling by car seek shelter under an overpass. False! Opening windows actually make the situation worse. False! Especially in the early stages, a tornado can be causing damage on the ground even though a visible funnel cloud is not present. False! Wind currents are concentrated as they are squeezed under the overpasses and increase in speed. This increased speed with flying debris INCREASES the risk of injury or death. Dimmitt, Texas. NOAA Photo Library

May 2, 2006Geog Wall cloud of an approaching tornado NOAA Photo Library Questions?