Four people have been injured and about a hundred and fifty houses damaged when a tornado struck the town of Mountainburg in Crawford County, Arkansas, on the afternoon of Friday 13 April 2018. A number of people were trapped in their homes by fallen debris following the incident, and local authorities were forced to issue a warning to sightseers to keep away, as they were hampering rescue attempts by emergency services.
Damage caused by a tornado in Mountainburg, Arkansas, on 13 April 2018. AccuWeather/Crawford County Department of Emergency Management.
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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