Around 140 000 people lost their electricity after a tornado hit in Dallas, Texas, on Sunday 20 October 2019. The storm touched down near Love Field Airport, then moved northeast through the city. The storm is known to have injured three people in the city and caused extensive damage to property, with weather monitoring radar systems detecting debris from the storm 6 km in the air, but no fatalities have been reported. One person has died in Arkansas after being hit by a falling tree due to high winds from a related weather system.
Tornado in Texas on 20 September 2019, seen from Rockwall, to the north of Dallas. AP.
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 Minnesota, which is fuelled 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 tornado events.
Simplified diagram of the air currents that contribute to tornado formation in Tornado Alley. Dan Craggs/Wikimedia Commons/NOAA.
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