Tornadoes

People and animals impacted by a tornado may be killed or injured and lose their homes and habitats. Plants may be uprooted, broken off, or damage.

Tornadoes come in a variety of shapes. Most commonly they appear as an elephant truck or elongated cone. In other cases they may take the shape of a wider cone, or an hourglass. Some appear as simple vertical columns while others look like massive wedges driven into the ground.

The vast majority of southern hemisphere tornadoes rotate clockwise. A small percentage rotate counterclockwise.

Yes. Population density does not affect the likelihood of a tornado striking. Many tornadoes have hit cities.

Both tornadoes are small-scale vortices of wind in which air spirals in toward a localized center of low pressure and then spirals up. Both produce strong winds over small areas, though tornadoes are far stronger. The formation of both depends on the conservation of angular momentum; they form when a larger, less intense circulation tightens and intensifies. The key difference between tornadoes and dust devils is that dust devils form from surface convection resulting from direct heating of the ground while tornadoes are driven by the movement of air in a thunderstorm.

A typical tornado lasts 1-5 minutes.

The most important tool in monitoring tornadoes is Doppler radar, which can detect tornadoes and the rotation that can cause them. They also use modern communication systems, which allows people to quickly relay eyewitness reports.

Tornadoes are most common in the northern and eastern parts of Texas, including the Panhandle.

The Tri-State tornado struck on the afternoon of Wednesday, March 18, 1925.

Doppler radar scans storms for rotation in thunderstorms, which indicates that a tornado is occurring or that one may soon develop. Eyewitnesses can relay reports of rotation, funnel clouds, and tornadoes on the ground. If reports indicate that a tornado has formed or is likely to form then officials issue a tornado warning. Information on the storm is broadcast online and through television and radio. Sirens may sound in some areas.

less than a year

The Waco, Texas tornado destroyed a significant portion of the city of Waco. Several multi-story brick buildings were destroyed in downtown Waco. Elsewhere in the city many homes were destroyed, some swept clean off their foundations.

Tornadoes form from thunderstorms, which are fueled by warm, moist air. Such warm, moist conditions occur most often during the summer. Tornadoes themselves are more common in the spring, when upper-level winds are more favorable for them to form.

If general conditions are favorable for tornadoes, but an are is not under an imminent threat, authorities issue a tornado watch. Notice of watches is broadcast through the National Weather Service website, weather radio, and routine weather reports. If a tornado is detected or if a storm may soon produce one, authorities issue a tornado warning. Warnings are broadcast through the means mentioned above as well as through emergency TV and radio broacasts and smartphone apps. Warning sirens may sound in some areas.

Tornadoes occur during severe thunderstorms and so are often preceded by heavy rain, strong winds, and hail. Specific signs that a tornado may soon develop include rotation in the clouds, a persistent lowering of the cloud base in or near that rotation, and a clear slot opening up near the rotation.

Some people report seeing greenish clouds before or during a tornado. While this phenomenon does sometimes occur, it is not necessarily associated with tornadoes.

Yes. As of October 19, 2015 the last reported tornado in the U.S. was an EF0 in southern California on October 17. So far all tornadoes in October 2015 have been weak, causing little or no damage.

Scientists thing that tornadoes usually dissipated when rain-cooled air chokes off the updraft of the tornado's parent storm, which is fueled by warm air. The cold air causes the updraft to weaken.

The outbreak that produced the Joplin tornado started on May 21. A large mass of warm, moist air was over the plains as a low pressure system pulled cooler, drier air from further north, forming a cold front that traveled westward, generating lift that ignited violent thunderstorms which began producing tornadoes. These thunderstorms continued through May 22. One particularly powerful storm developed over eastern Kansas and soon after crossing into Missouri, produced a tornado 1 mile west of Joplin that intensified extremely rapidly.

The effects of tornadoes are local rather than global. Tornadoes can devastate towns, sometimes destroying whole neighborhoods. The damage and loss of productivity can badly damage an area's economy.

The Great Plains are the most tornado-prone region in the world, earning the title Tornado Alley. The Deep South, particularly in Alabama and Mississippi, also has a high incidence of strong tornadoes, forming a region known as Dixie Alley. Florida also has a high incidence of tornadoes, comparable to that of Tornado Alley, but the tornadoes in Florida are weaker than in other tornado-prone regions. Finally, some suggest that there is a "Hoosier Alley" covering parts of Illinois, Indiana, Ohio and Michigan.

Doppler radar can be used to measure at a distance how fast the wind is moving towards or away from the radar. Because of this ability, we can used Doppler radar to detect the rotation in a thunderstorm that either indicates a tornado or might become one. Radar provides a huge advantage since it can scan a large area in a matter of minutes and detect tornadoes even when nobody is around to see them or if they are obscured by rain or the dark of night.

Yes. The rotation of a tornado can be detected using doppler radar. Additionally, many tornadoes can be seen with the naked eye.

Under these circumstances a tornado warning would be issued.

Most deaths and injuries in tornadoes result from flying debris. Others may be injured by falling objects and the walls and ceilings of collapsing buildings. Some people are injured as a result of being thrown by the tornado, though few survive being carried long distances.

The main way we avoid loss of life is through warnings, which give people a chance to get to a safer place. Some buildings and homes in tornado-prone regions have tornado shelters that are nearly impossible for a tornado to penetrate. Some homes are build with structural enhancements including hurricane ties to hold the roof in place, closely spaced supports to strengthen the walls, and anchor bolts to secure a house to its foundation more firmly than other attachments.