Sunday 19 May 2013

Texas Tornado kills six.

A tornado described as a 4 on the Enhanced Fujita Scale (wind seeds between 267 and 322 kph) by the National Weather Service, hit the north Texas town of Granbury on the evening of Wednesday 15 May 2013, devastating the Rancho Brazos neighborhood and killing six people. 58 properties were either destroyed or damaged (out of 110 in the subdivision) and 37 more people hospitalized, at least six more people are still missing. At least 16 tornadoes were produced by the 15 May storm, though no others appear to have caused as much damage as the one which hit Rancho Brazos.

Rescue workers searching through the remains of a house in Granbury, Texas, on 16 May 2013. Brandon Wade/Reuters.

Tornadoes are formed by winds within large thunder storms called super cells. Supercells are large masses of warm water-laden air formed by hot weather over the sea, when they encounter winds at high altitudes the air within them begins to rotate. The air pressure will drop within these zones of rotation, causing the air within them so rise, sucking the air beneath them up into the storm, this creates a zone of rotating rising air that appears to extend downwards as it grows; when it hits the ground it is called a tornado. Tornadoes can occur anywhere in the world, but are most common, and most severe, in the area of the American mid-west known as 'Tornado Ally', running from Texas to Minnisota, which is fueled by moist air currents from over the warm enclosed waters of the Gulf of Mexico interacting with cool fast moving jet stream winds from the Rocky Mountains. Many climatologists are concerned that rising temperatures over the Gulf of Mexico will lead to more frequent and more severe typhoon events.

The air currents over Tornado Alley. University of Illinois at Urbana Champaign

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