understanding a tornado
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Understanding a Tornado
A tornado is a violently rota/ng column of air that is in contact with both the surface of the earth and a cumulonimbus cloud. They are o:en referred to as twisters or cyclones. However, the word cyclone is used in a wider sense in meteorology for closed low pressure circula/on. Tornadoes come in many shapes and sizes, but they are typically in the form of a visible condensa/on funnel, whose narrow end touches the earth and is o:en encircled by a cloud of debris and dust. The most extreme tornadoes can a@ain wind speeds of more than 300 miles per hour. Tornadoes have been observed on every con/nent except Antarc/ca. However, the vast majority of tornadoes occur in the Tornado Alley region of the United States, although they can occur nearly anywhere in North America. They also occasionally occur in south-‐central and eastern Asia, 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 pa@erns in velocity and reflec/vity data, such as hook echoes or debris balls, as well as by the efforts of storm spo@ers.
Recently, a tornado, with peak winds es/mated at 210 miles per hour struck Moore, Oklahoma and adjacent areas killing 23 people and injuring 377 others. The tornado was part of a larger weather system that had produced several other tornadoes over the previous two days. Despite the tornado following a roughly similar track to the even deadlier 1999 Bridge Creek–Moore tornado, very few homes and neither of the stricken schools had purpose-‐built storm shelters. Though tornadoes can strike in an instant, there are precau/ons and preventa/ve measures that people can take to increase the chances of surviving a tornado. Authori/es such as the Storm Predic/on Center advise having a pre-‐determined plan should a tornado warning be issued. When a warning is issued, going to a basement or an interior first-‐floor room of a sturdy building greatly increases chances of survival. In tornado-‐prone areas, many buildings have storm cellars on the property. These underground refuges have saved thousands of lives.
Some countries have meteorological agencies which distribute tornado forecasts and increase levels of alert of a possible tornado, such as tornado watches and warnings in the United States and Canada. Weather radios provide an alarm when a severe weather advisory is issued for the local area, though these are mainly available only in the United States. Unless the tornado is far away and highly visible, meteorologists advise that drivers park their vehicles far to the side of the road and find a sturdy shelter. If no sturdy shelter is nearby, ge\ng low in a ditch is the next best op/on. Highway overpasses are one of the worst places to take shelter during tornadoes, as the constricted space can be subject to increased wind speed and funneling of debris underneath the overpass.