When do tornadoes happen

Using units F0 to F5, the Fujita scale measures a tornado's intensity by analyzing the damage the twister has done and then matching that to the wind speeds estimated to produce comparable damage.

The United States now uses the EF Enhanced Fujita scale , which takes more variables into account when assigning wind speeds to a tornado. Every year in the United States, tornadoes do about million dollars in damage and kill about 70 people on average. Extremely high winds tear homes and businesses apart. Winds can also destroy bridges, flip trains, send cars and trucks flying, tear the bark off trees, and suck all the water from a riverbed.

High winds sometimes kill or injure people by rolling them along the ground or dropping them from dangerous heights. 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. India bets its energy future on solar—in ways both small and big.

Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country. Continue Reading. How Do Wildfires Start? The past several years wildfires have been rampant, ravaging parts of California, Colorado, Oregon, and Washington. In alone, 8. Why do these wildfires seem to be getting more intense and more frequent with time?

Hot, dry Warning Signs of a Tornado Mother Nature gives us clues as to what she is about to do. Dark clouds often signal rain and thunder tells us a storm is coming. There are also a variety of signs that a tornado is coming.

Signs that when heeded can mean the difference between life and death. If you are in Differences Between Tropical Storms and Hurricanes During hurricane season , the news is filled with stories about tropical storms and hurricanes heading toward U.

For many homeowners in coastal regions, these storms are common and expected given the location. However, there are many who may be confused about the Page 1 of You may have heard another term—storm chaser—but that really refers to people who chase tornadoes and storms for a hobby. Research meteorologists have a scientific purpose behind their pursuit of severe weather.

They have to come up with questions they think they can answer by taking certain measurements. What are the wind speeds in a tornado? We're not really sure what the highest wind speed might be inside a tornado, since strong and violent tornadoes destroy weather instruments. We really only have measurements of the winds inside weaker tornadoes. How fast do tornadoes move? We don't have detailed statistics about this. Movement can range from almost stationary to more than 60 mph.

A typical tornado travels at around 10—20 miles per hour. How long is a tornado usually on the ground? Detailed statistics about the time a tornado is on the ground are not available.

This time can range from an instant to several hours. The average is about five minutes. The movie Twister was based upon work NSSL did in the mids using a gallon drum outfitted with various meteorological sensors. NSSL tried for several years to put it in the path of an oncoming tornado, but had minimal success.

It is possible that the technology could exist someday; however there are significant challenges with observations such as these. Read more about Twister science Has every state had a tornado? Yes, although some states have many more tornadoes than others. Are there tornadoes in the Arctic Circle?

We are not aware of any tornadoes occurring in the Arctic Circle. Tornadoes need moisture and warm air to form, which is unusual at that latitude. Plus tornadoes or their evidence have to be observed by someone, and the Arctic Circle has few residents!

Do tornadoes really stay away from gullies, rivers and mountains? A gully could actually make a tornado more intense, just as an ice skater spins faster when he or she stands up tall and stretches their arms up straight over their heads.

Every major river east of the Rockies has been crossed by a significant tornado, and high elevations in the Appalachians, Rockies, and Sierra Nevada have all experienced tornadoes.

Do tornadoes always come from a wall cloud? A wall cloud is not always present. It is also possible that you cannot see a wall cloud because of your viewing angle or low level clouds. What does a tornado sound like? People who have been in a tornado say it sounds like a jet engine or a freight train and is very loud. They said it hurt their ears, but they were more worried about what might happen to them than they were about the pain in their ears.

Can tornadoes be stopped? You have to consider that the tornado is part of something bigger: the supercell thunderstorm. Unless you disrupt the supercell thunderstorm itself, you would likely have another tornado, even if you were able to destroy the first.

The thunderstorm's energy is much greater than the tornado. No one has tried to disrupt the tornado because the methods to do so could likely cause even more damage than the tornado. Detonating a nuclear bomb, for example, to disrupt a tornado would be even more deadly and destructive than the tornado itself.

Lesser tactics like deploying huge piles of dry ice or smaller conventional weaponry would be too hard to get into the right place fast enough, and would likely not have enough impact to affect the tornado much anyway. Thunderstorms, and all of the hazards they produce, are part of a natural earth cycle.

Taking actions sufficient to disrupt this cycle could lead to unintended consequences. What is the difference between a tornado watch and a tornado warning? A tornado watch defines an area where tornadoes and other kinds of severe weather are possible in the next several hours.

It means that you need to be alert, and be prepared to go to safe shelter if tornadoes happen or a warning is issued. Tune in to local TV, radio or internet for more information. A tornado warning means that a tornado has been spotted, or that Doppler radar shows a thunderstorm circulation which can spawn a tornado. When a tornado warning is issued for your area, seek safe shelter immediately.

The Storm Prediction Center issues tornado and severe thunderstorm watches. Your local National Weather Service office issues tornado warnings, as well as thunderstorm warnings, which include the possibility of tornadoes. What would it be like to be in the eye of a tornado? This is a fiction largely caused by the movie Twister. How many tornadoes hit the US each year? About , though it can vary significantly from year to year or location to location.