How do tornadoes start

But most tornado victims are struck by flying debris—roofing shingles, broken glass, doors, metal rods. The number of average deaths per year in the United States used to be higher before improved forecasting and warning systems were put into place. Meteorologists at the U. National Weather Service use Doppler radar, satellites, weather balloons, and computer modeling to watch the skies for severe storms and tornadic activity.

Doppler radars record wind speeds and identify areas of rotation within thunderstorms. Since Doppler radar has been in use, the warning time for tornadoes has grown from fewer than five minutes in the s to an average of 13 minutes by the late s. A supercell thunderstorm strikes in South Dakota. Among the most severe storms, supercells can bring strong winds, hail, and even tornadoes. See more extreme weather pictures.

When weather conditions are conducive for tornado formation, the National Weather Service issues a tornado watch. When a tornado has been sighted or indicated on radar, a tornado warning is issued.

Some scientists, meteorology buffs, and adrenaline junkies hit the road during tornado season to chase storms. Researchers race to place sensors in tornadoes' paths. The sensors measure data such as wind speed, barometric pressure, humidity, and temperature. The challenge for researchers is being in the right place at the right time. Every morning they study weather conditions and head for the area that seems most likely to spawn a twister.

They drive through severe storms, dodge lightning, face flash floods, and get pounded by hail—sometimes for years—before ever spotting a tornado.

All at considerable risk. In , National Geographic Explorer Tim Samaras and his team were killed while trying to study a tornado in Oklahoma. See photos of Samaras's work. All rights reserved. What is a tornado? Lightning Strikes A supercell thunderstorm strikes in South Dakota. Share Tweet Email. Why it's so hard to treat pain in infants. This wild African cat has adapted to life in a big city. Animals Wild Cities This wild African cat has adapted to life in a big city Caracals have learned to hunt around the urban edges of Cape Town, though the predator faces many threats, such as getting hit by cars.

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Animals Wild Cities Wild parakeets have taken a liking to London. Animals Wild Cities Morocco has 3 million stray dogs. So, in that way, they are somewhat predictable. But no one ever knows when, where, how intense, and how many tornadoes a thunderstorm will create. Conditions are ripe for tornadoes when the air becomes very unstable, with winds at different altitudes blowing in different directions or at different speeds—a condition called wind shear.

The first result is a large thunderstorm. Inside the huge thundercloud, warm and humid air is rising, while cool air is falling, along with rain or hail. All these conditions can result in rolling, spinning air currents inside the cloud. Although this spinning column of air starts out horizontal, it can easily go vertical and drop down out of the cloud. When it touches the ground, it's a tornado. The winds inside the spinning column of some tornadoes are the fastest of any on Earth.

They have been clocked at over miles per hour! Sometimes the spinning column of air lifts off the ground, then touches down again some distance along its path. It's hard to measure the winds in a tornado directly. So they are evaluated by the amount of damage they do. Here is a scale meteorologists use to describe tornado intensity based on damage.

These satellites can more quickly monitor the motion of clouds to identify a severe storm as soon as it develops. Tornadoes What is a tornado? A tornado is a violent rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of up to mph.

They can destroy large buildings, uproot trees and hurl vehicles hundreds of yards. They can also drive straw into trees. Damage paths can be in excess of one mile wide to 50 miles long. In an average year, tornadoes are reported nationwide. How do tornadoes form? Most tornadoes form from thunderstorms.