Natural disasters Tornadoes
...Most tornadoes last less than 10 minutes. Rain, wind, lightning, and hair vary from storm to storm. Large hail can indicate an unusually dangerous thunderstorm, and can happen before a tornado. A waterspout is a tornado over water, this means it is a non-supercell tornado. These are common on the southeast U.S. coast, off southern Florida and the Keys. They can happen over seas, bays and lakes worldwide. Even though waterspouts are always tornadoes by definition, they don’t count in tornado records unless they hit land. They are a lot smaller and weaker. Waterspouts can overturn small boats, damage ships, cause significant damage when they hit land, and kill people. Most tornadoes, but not all of them, rotate cyclonically, which is counterclockwise in the northern hemisphere and clockwise south of the equator. Anticyclonic tornadoes, which rotate clockwise in the northern hemisphere, usually are in the form of waterspouts. The way they measure degree of damage to the intensity of the wind is with what is called the “F-SCALE. This was invented by a man named Dr. T. Theodore Fujita. Wind speeds on the “F-SCALE” have never been scientifically tested and proven. Meteorologists and engineers that have many years experience in damage survey techniques may come up with different “F-SCALE” ratings for the same damage. A lot depends on how well built a structure is, wind speeds, wind duration, wind direction, amount of debris flying around plus many other factors. The scale basically ranges from an F0 to an F5. F0 is the low end of scale, but could still cause significant damage to a well built home at its peak. They measure the wind speed with Doppler radar. A tornado with a wind speed greater than 318mph is rated an F5. Whether a tornado is wide like a wedge or skinny like a rope, it does not say anything about its strength. Some small rope type tornadoes can still cause violent damage. Some very large wedge type tornadoes that stretch over a quarter mile are very weak, but still cause damage. Depending on what a tornado is hitting, its size, closeness and other factors, it could sound like a continuous rumble, similar to a train. Sometimes they sound like a loud whooshing sound, like a water fall or an open car window when driving fast. Or sometimes it can just sound like a really loud roar. Sometimes loud thunderstorms can sound like a loud roar too. Often hurricanes and tropical storms produce tornadoes, but not always. Each storm varies a great deal. Some landfalling hurricanes in the U.|S. fail to produce any known tornadoes, while others cause major outbreaks. It is unknown how many tornadoes hurricanes produce over the water. In Canada the Meteorological Service of Canada are the ones who usually forecast tornadoes. When predicting severe weather a day or two in advance, they look for temperature and wind flow patterns in the atmosphere which can cause enough moisture, instability, lift, and wind shear for tornadic thunderstorms. It sound so easy but the combination of these four items must be present in the right amounts in order to have a tornado. It varies so much from each situation sometimes it’s not possible to tell in advance....