How fast tornadoes can go

After a tornado has come and gone, scientists look at the amount of damage that it caused to figure out the strength of the twister. They use the Enhanced Fujita EF Scale - six categories that describe how tornado damage relates to wind speeds. According to the scale, EF0 is the weakest tornado category with gusts up to 85 mph kph and EF5 is the strongest tornado with wind gusts over mph kph.

In general, tornadoes fall into three types: weak tornadoes, strong tornadoes, and violent tornadoes based on the tornado size, how long it lasts and how much damage it causes. Tornadoes can occur anywhere in the world. Skip to main content. 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. They are also better at understanding what's actually going on inside the cloud: what characteristics the cloud has that indicate a severe storm and how much lightning it produces.

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. What are some other factors for tornadoes to form?

Several conditions are required for the development of tornadoes and the thunderstorm clouds with which most tornadoes are associated. Once the air begins to rise and becomes saturated, it will continue rising to great heights to produce a thunderstorm cloud, if the atmosphere is unstable.

An unstable atmosphere is one where the temperature decreases rapidly with height. Finally, tornadoes usually form in areas where winds at all levels of the atmosphere are not only strong, but also turn with height in a clockwise or veering direction.

What do tornadoes look like? Tornadoes can appear as a traditional funnel shape, or in a slender rope-like form. Can more than one tornado form at a time? Yes, one way that twin tornadoes can occur is through a processes called occlusion. This happens when one tornado starts to dissipate as cool, moist air wraps around the tornado while another tornado begins to form in a more favorable part of the thunderstorm. Another term for this is cycling and that process is fairly common in very strong thunderstorms.

The overlap time for both tornadoes to be on the ground concurrently is a very short time. Another way two tornadoes can form is from a multiple-vortex tornado. This is because of smaller tornadoes inside the larger tornado have stronger winds and are spinning much faster than the larger tornado. The last way that twin tornadoes can occur is by satellite tornadoes.

This occurs when a second tornado develops independently of the primary tornado. The satellite tornado orbits the primary tornado but is located inside the same mesocyclone — this means there are two separate areas of rotation occurring at the same time in the atmosphere.

What is a funnel cloud? A funnel cloud is a rotating cone-shaped column of air extending downward from the base of a thunderstorm, but not touching the ground. When it reaches the ground it is called a tornado. What is a supercell thunderstorm?

A supercell thunderstorm is a long-lived thunderstorm whose updrafts and downdrafts are in near balance. These storms have the greatest tendency to produce tornadoes that stay on the ground for long periods of time. Supercell thunderstorms can produce violent tornadoes with winds exceeding mph. What is a mesocyclone? A mesocyclone is a rotating vortex of air within a supercell thunderstorm. Mesocyclones do not always produce tornadoes. What is a microburst? A microburst is a downdraft sinking air in a thunderstorm that is less than 2.

Although microbursts are not as widely recognized as tornadoes, they can cause comparable, and in some cases, worse damage than some tornadoes produce. In fact, wind speeds as high as mph are possible in extreme microburst cases. What is a wall cloud? A wall cloud is an abrupt lowering of a rain-free cumulonimbus base into a low-hanging accessory cloud. A wall cloud is usually situated in the southwest portion of the storm. A rotating wall cloud usually develops before tornadoes or funnel clouds.

What is a hook echo? A hook echo describes 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 relative to the motion of the storm.

A hook is often associated with a mesocyclone and indicates favorable conditions for tornado formation. The hook is caused by the rear flank downdraft and is the result of precipitation wrapping around the back side of the updraft. What is a waterspout? A waterspout is just a weak tornado that forms over water. They are most common along the Gulf Coast. Waterspouts can sometimes move inland, becoming tornadoes causing damage and injuries.

What is hail? Hail is created when small water droplets are caught in the updraft of a thunderstorm. These water droplets are lifted higher and higher into the sky until they freeze into ice. Once they become heavy, they will start to fall. If the smaller hailstones get caught in the updraft again, they will get more water on them and get lifted higher in the sky and get bigger.

Once they get lifted again, they freeze and fall. This happens over and over again until the hailstone is too heavy and then falls to the ground. What is the largest hailstone recorded in the United States? According to the National Weather Service, the largest hailstone is 8 inches in diameter and weights approximately 2 pounds.

It fell in Vivian, South Dakota on July 23,