Twisters or Tornadoes
What is a tornado?
The word tornado comes from the Spanish or Portuguese verb “tornar”, that means “to turn”.
A tornado is an extremely intensive windstorm known by a twisting, funnel shaped cloud. Also it’s defined as a violent rotating column of air in contact with the ground and pendent from a swirled cloud. This formation is visible for the presence of dust that is sucked from the ground and for the water’s condensation in its centre.
Tornadoes from severe thunderstorms usually happen as a result of a hurricane.
How do tornadoes form?
Tornado’s steps
1- Before thunderstorm develop a change in wind direction and an increase in wind speed creates an invisible horizontal spinning effect in the lower atmosphere.
2- Rising air within the thunderstorm updraft hits the rotating air from horizontal to vertical.
3- An area of rotation of 2 to 6 miles wide now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.
Tornado’s formation occurs when cool air over takes a layer of warm air forcing the warm air to rise rapidly, but a more detailed explanation would be that tornadoes born in the hurricane’s walls, owing to the fact that two opposite strengths confront, the wind strength turns in circles (all this happens for the rotation movement of the earth, like the hands of a watch, in the south hemisphere, but on the other way in the north hemisphere, although sometimes they can change its behavior) and the suction force that is created when the warm air is sucked and ups until the coldest zones, where it generates more suction that makes the phenomenon more powerful.
Tornadoes’ classification
The method of measuring tornadoes in known as the Fujita Scale, this scale measures a tornado’s intensity by the damage that it causes, and by its wind speed. A tornado can be:
*F0= wind speeds up to 73 miles per hour (115 km/h), light damage (branches broken off trees, damage to chimneys)
*F1= wind speeds 73 to 112 miles per hour (116-118 km/h), moderate damage (moving cars blown off roads, mobile houses pushed off foundations)
*F2= wind speeds 113 to 157 miles per hour (181-250 km/h), considerable damage (mobile homes demolished, cars lifted off ground)
*F3= wind speeds 158 to 206 miles per hour (251-330 km/h), severe damage (trains overturned, most trees in forest uprooted)
*F4= wind speeds 207 to 260 miles per hour (331-415 km/h), devastating damage (well constructed houses leveled, structures with weak foundations blown away some distances)
*F5= wind speeds 261 to 318 miles per hour (415-510 km/h), incredible damage (strong frames houses leveled off foundations and swept away, trees debarked, cars fly away)
In the movie Twister an F5 was considered as “The finger of God”, people believed that God was dragging a finger across the earth wiping out all the things that were in his path.
How often do tornadoes occur?
Tornadoes occur all over the world, but the most affected region measured by the numbers of tornadoes per unit area is United Kingdom, especially England. In Canada, an average of 80 tornadoes occur annually causing tens of millions of dollars in damage. On the other hand the United States experience is dramatic, because this country has been the victim of the strongest tornadoes, in US an approximately 100.000 thunderstorms occur in one year causing 1.000 tornadoes and almost 50 deaths per year.
Tornadoes in Chile
The lower temperatures in Chile make impossible the formation of a tornado, but, however in our history there are two phenomenon that were considered as a tornado, both in the north of our country, the first one occurred between Iquique and Antofagasta on June 20, 1929, a violent hurricane swirled the dunes of Iquique, invading almost all the city and parts of La Pampa, Antogfagasta y Chañaral. The second case, in Antofagasta, happened on July of 1954 killing two kids. These two phenomenons didn’t have the characteristics formation of a tornado, and even in the second one, the wind speed was just 80 km/h, and that speed in not enough for call it tornado.
How can we protect us of a tornado?
The forms of protection are very similar to the ways of a hurricane, but the emergency in bigger because a tornado is faster and unpredictable. The safest refuge is a basement or a room in the middle of the house without windows.
In United States, the authorities warn to the community through a “watching” when the conditions of a tornado are favorable, and a “warning” when a tornado begins in some near place. In tornado season, the government spends time educating people about the damages and what they can do to improve the chances of surviving a storm.
There is no way to be sure when exactly a tornado can occur, but with the new technologies that bring us advises a few minutes before a tornado, many lives can be saved.
