How do tornadoes form? Most tornadoes form from thunderstorms. You need warm, moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere. A change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the updraft tilts the rotating air from horizontal to vertical. An area of rotation, miles wide, now extends through much of the storm.
Most strong and violent tornadoes form within this area of strong rotation. Enhanced, Operational Fujita Scale. How do tornadoes form? See our explanation in the Tornado Types section. Can tornadoes be predicted? Yes, but only to a limited extent. Although the process by which tornadoes form is not completely understood, scientific research has revealed that tornadoes usually form under certain types of atmospheric conditions.
When forecasters see those conditions, they can predict that tornadoes are likely to occur. However, it is not yet possible to predict in advance exactly when and where they will develop, how strong they will be, or precisely what path they will follow.
Once a tornado is formed and has been detected, warnings can be issued based on the path of the storm producing the tornado, but even these cannot be perfectly precise about who will or will not be struck. What are the people called who study tornadoes? People who study tornadoes are just research meteorologists or atmospheric scientists. 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.
In order to make a close estimate, Dr. Ted Fujita developed a scale back in After some adjustments in the early s from Dr. Fujita himself and a consensus from a panel of meteorologists and engineers in the early s, we now used what is called the Enhanced Fujita EF Scale. There are a few tell-tale signs a tornado may develop. The most common warning is a funnel shaped cloud. If you see a rotating cloud in the shape of a funnel slowly making its way towards the earth, it can become a tornado.
Another obvious warning sign is falling debris. Next you should watch out for an incredibly dark sky or a dark sky with a greenish tint. The green coloring comes from sunlight reflecting off hail stones, which typically accompany tornadoes and the storms that precede them. In some cases, there can be an eerie calm after a strong thunderstorm has occurred before a tornado hits. This is because tornadoes form on the rear right quadrant of strong thunderstorms and away from the heaviest rain and hail.
You should not go out immediately after a strong storm has ended; especially if you have been under a tornado warning. You can also tell a tornado is on the way if you hear loud, persistent roar. This continuous rumble will sound a lot like a freight train and is a sign that a tornado could occur or already has occurred and is closing in.
There is another warning sign a tornado may occur that you might not be able to tell on your own. That sign is a high frequency of in-cloud lightning. This can be tricky to spot on your own because in-cloud lightning never touches the ground.
Warning systems that utilize total lightning detection can detect these high frequencies and give people more time to prepare for possible tornadoes. Another way to protect yourself from tornadoes is by paying attention to tornado watches and warnings. The National Weather Service NWS shares tornado watches and tornado warnings to help people stay updated on the chances of severe weather. How do you predict a tornado?
Predicting exactly when and where a tornado will form and move is not possible with current technology. However, meteorologists can predict tornadoes by looking for conditions that are favorable for tornado development. They mail do this by using the output from very powerful computer forecast models. Massive computer programs called numerical weather prediction models help meteorologists decide if conditions will be right for the development of a tornado.
These models gather data from weather balloons twice per day in addition to data from satellites, aircraft, and surface weather stations. If each run looks similar, then meteorologists can assume the weather will likely follow the rules.
However, if the runs look different in different places then meteorologists understand something in the atmosphere is causing the weather to misbehave. There is also the aspect of total lightning detection. Since high frequencies of in-cloud lightning can be a warning sign a tornado has formed or could form, meteorologists and everyday users who rely on total lightning detection systems can keep an eye on in-cloud lightning frequencies to help predict.
A lot of tornado detecting is based on what forecasters and storm spotters or storm chasers Like our meteorologist, Mark Ellinwood can see with their bare eyes. There are certain thunderstorm features like green sky or a funnel-shaped cloud that help people predict them. There are more advanced visual cues as well like a rear-flanked downdraft. Storm spotters are trained to recognize tornadic conditions and report what they see to the National Weather Service.
The other way we detect tornadoes is with radar imagery. Patterns in radar, like the tornadic vortex signature TVS , are a good indication that a tornado has developed. Computer programs, called algorithms, analyze Doppler radar data and display it in ways that make it easier for forecasters to identify tornadoes.
When a Doppler radar detects a large, rotating updraft that occurs inside a supercell, it is called a mesocyclone. Mesocyclones are typically miles in diameter. This is much larger than the tornado that may develop within in. Another pattern important for tornado detection is a hook echo. This is a pattern in radar reflectivity images that looks like a hook extending from the radar echo, usually in the right-rear part of the storm.
The hook is often associated with a mesocyclone and indicated favorable conditions for tornado formation. Another way we currently detect tornadoes is with dual-polarization radar technology which allows organizations like the National Weather Service to see debris. This gives meteorologists a high-degree of confidence a damaging tornado is on the ground.
When you have solid plan for any type of severe weather event you are more likely to survive. Can you survive being caught in a tornado? Yes, of course. But only if you know what to do before, during, and after. The United States government advises citizens to do the following before a tornado in order to remain safe:. In the U. These include a rotating, funnel-shaped cloud; an approaching cloud of debris; or a loud roar. If your community has sirens, then become familiar with the warning tone.
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