 A tornado is a rapidly rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. The windstorm is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name the weather system with a low pressure aria in the center around which winds below counterclockwise in the northern hemisphere and clockwise in the southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speed less than 110 miles per hour 180 kilometers slash h are about 250 feet 80 meters across and travel a few miles several kilometers before dissipating. The most extreme tornadoes can attain wind speed of more than 300 miles per hour 480 kilometers slash h are more than 2 miles 3 kilometer in diameter and stay on the ground for dozens of miles more than 100 kilometers. Various types of tornadoes include the multiple vortex tornado, landspout and waterspout. Waterspouts are characterized by a spiraling funnel shaped wind current, connecting to a large cumulus or cumulonimbus cloud. They are generally classified as non-supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes. These spiraling columns of air frequently develop in tropical areas close to the equator and are less common that high latitudes. Other tornado-like phenomena that exist in nature include the dust-nado, dust-devil, fire-warls, and steam-devil. Tornadoes occur in North America, particularly in the area of the United States, known as Tornado Valley, as well as in northern and east-central South America, southern Africa, northwestern and southeast Europe, western and southeastern Australia, and New Zealand. Tornadoes can be detected before or as they occur through the use of pulse-doppler radar by recognizing patterns in velocity and reflectivity data, such as hope echoes for debris falls, as well as through the efforts of storm spotters.