1. 1. TORNADOESTORNADOES DENISE SZILAGYI
2. 2. What is a tornado? Tornadoes are relatively small, localized low- pressure areas associated with powerful thunderstorms under cumulonimbus clouds. The typical tornado is 820 feet in diameter, with whirling winds of about 150 miles per hour. The twisting funnel cloud typically travels at about 40 miles per hour over the surface. Most tornadoes (but not all!) rotate cyclonically, which is counterclockwise in the northern hemisphere and clockwise south of the equator.
3. 3. How are tornadoes formed?
4. 4. In order for a vortex to be classified as a tornado, it must be in contact with the ground and the cloud base.
5. 5. Main types of tornadoes Rope tornadoes Wide tornadoes
6. 6. Where do tornadoes occur?
7. 7. Tornadoes are most consistently associated with fast-moving cold fronts that sweep across the midsection of the United States, drawing warm, moist, tropical air from the Gulf of Mexico. The cold front is usually associated with a strong low-pressure storm system that rotates counterclockwise as it swirls across land in the prevailing westerly wind pattern.
8. 8. Tornadoes can appear from any direction. Most move from southwest to northeast, or west to east. Some tornadoes have changed direction amid path, or even backtracked. Hail, any particular pattern of rain, lightning or calmness, are not reliable predictors of a tornado threat. Tornadoes can last from several seconds to more than an hour, however most tornadoes last less than 10 minutes.
9. 9. How is life on Earth affected by Tornadoes?
10. 10. Damage Oklahoma, 2013
11. 11. Some of the damage caused by tornadoes results from the rapid passage of low pressure. Most houses are built to withstand downward pressure from much water, snow, or wind against the structure, especially weight on the roof. When a tornado passes over a house, however, the low pressure above, countered with high pressure inside that cannot leak out quickly enough plus wind pressure under the eaves, causes the house to appear to explode from within.
12. 12. Solutions to better predict tornadoes
13. 13. The most widely used method worldwide, for over three decades, was the F-scale developed by Dr. T. Theodore Fujita. In the U. S., and probably elsewhere within a few years, the new Enhanced F-scale is becoming the standard for assessing tornado damage.
14. 14. The National Weather Service usually can predict severe weather regions several hours in advance, but the exact location of a tornado must wait for a visual sighting or the occurrence of a tornado signature on Doppler radar.
15. 15. Balloons carry instrument packages aloft twice a day from about 90 of the 250 weather stations of the continental United States.
16. 16. When dangerous storms begin to develop, Doppler radar is available in most parts of the nation. Doppler radar detects the wind component parallel to the radar beam, then examines the pattern of the wind field to find locations of potential tornadoes.
17. 17. Meteorologists continue to improve their ability to forecast, locate, and track tornadoes. Space satellites, a worldwide network of manned weather stations, and sophisticated computer systems enable meteorologists to see weather as it develops.