Why do tornadoes start?

Answer 1

They don't happen instantly, but they do certainly form quickly compared with other types of storm. This simply has to do with the scale on which they exist. In weather terms tornadoes are microscale weather patterns, referring to things that are less than a few kilometers in size. (The largest known tornado was 4 km, or 2.5 miles wide. Most are much smaller.)

Because of their small size the mechanisms behind microscale systems operate quickly, causing them to form and dissipate in minutes or seconds in most cases. In addition to tornadoes, other microscale systems include turbulence and individual cumulus clouds.

Answer 2

Simply put tornadoes are a means by which storms release energy. These storms in turn have the function of redistributing heat and moisture on earth.

The formation of tornadoes is complicated and not fully understood. This is the best explanation scientists have so far.

First, a condition called wind shear, in which the speed or direction of the wind changes with altitude. If the shear is strong enough it can essentially tilt a thunderstorm, this separates the updraft and downdraft of the thunderstorm, preventing them from interfering with one another. This allows the storm to become stronger and last longer.

Additionally, if the wind shear is strong enough it can start the air rolling in what is called horizontal vorticity. This horizontal vorticity can then be turned vertical by a thunderstorm's updraft. When this happens, the thunderstorm may start rotating. The rotation is especially strong in an updraft called a mesocyclone. If the storm intensifies rapidly enough, a relatively warm downdraft called a rear-flank downdraft or RFD can wrap around the bottom part of the mesocyclone. This can then tighten and intensify its rotation and bring it down to the ground to produce a tornado.

Answer 3

Well, no one really knows exactly why tornadoes form.

There are two main ingredients needed for tornado formation: wind shear and thunderstorms.

Thunderstorms usually develop in warm, moist air in advance of eastward-moving cold fronts. These thunderstorms often produce large hail, strong winds, and tornadoes.

During the spring in the Central Plains, thunderstorms frequently develop along a "dryline," which separates very warm, moist air to the east from hot, dry air to the west. Tornado-producing thunderstorms may form as the dryline moves east during the afternoon hours.

Wind shear occurs when the speed or direction of the wind varies with altitude. This "tilts" a thunderstorm, separating the updraft region from the downdraft region, allowing the storm to become stronger and last for hours.

The wind shear can also induce what is called horizontal vorticity, which is simply rolling masses of air. The updraft of a storm can then turn this vorticity vertical. The newly rotating updraft is now called a mesocyclone, and the storm a supercell. The lower portion of the mesocyclone then tightens and intensifies, developing into what we know as a tornado. How this happens is not fully understood but it is widely believed that a downdraft wraps around the mesocyclone and "squeezes" it into a tighter vortex.

Tornadoes occasionally accompany tropical storms and hurricanes that move over land. Tornadoes are most common to the right and ahead of the path of the storm center as it comes onshore. In this case the necessary wind shear is produced as the low portions of the storm weaken fast than the upper portions. This wind shear can then turn storms in the outer bands to become supercells

Answer 4

Tornadoes occur when you have shifting winds the higher you go in a storm such as blowing from the north in a lower area of the storm and from the south in a higher area of the storm. If the storm has a strong enough updraft and strong enough downdraft that creates the rotation that then becomes a tornado.

Answer 5

The formation of tornadoes is complicated.

First, a condition called wind shear, in which the speed or direction of the wind changes with altitude. If the shear is strong enough it can essentially tilt a thunderstorm, this separates the updraft and downdraft of the thunderstorm, preventing them from interfering with one another. This allows the storm to become stronger and last longer.

Additionally, if the wind shear is strong enough it can start the air rolling in what is called horizontal vorticity. This horizontal vorticity can then be turned vertical by a thunderstorm's updraft. When this happens, the thunderstorm may start rotating. The rotation is especially strong in an updraft called a mesocyclone. If the storm intensifies rapidly enough, a relatively warm downdraft called a rear-flank downdraft or RFD can wrap around the bottom part of the mesocyclone. This can then tighten and intensify its rotation and bring it down to the ground to produce a tornado.

Answer 6

Tornadoes form when thunderstorm start rotating due to interaction between wind shear and thunderstorms. This rotation can tighten and intensify to produce a tornado.
There is no agreement among experts on any single theory of tornado formation.

Answer 7

Thunderstorms form as a result of instability which usually results from warm, moist air near ground level while there is a cold pool of air aloft. Since warm air is less dense the cold air it will tend to rise, but it needs something to start the upward motion. Sometimes local topography or localized convergence can trigger this, but in the middle latitudes the cause of lift is usually a large scale low pressure system or and associated cold front. When air is lifted it cools, and in most cases soon becomes cooler and thus denser than its surroundings, even though ambient temperature is generally lower the higher you go. The rate at which the air cools as you go up is called the environmental lapse rate. If the air is moist it may cool to the point that the moisture in it condenses, forming clouds. This condensation releases heat, slowing the rate at which the air cools. In some cases this causes the rising air to cool more slowly than the environmental lapse rate, so that it eventually becomes warmer than its surroundings. Now it can rise on its own, faster and higher than the initial lifting mechanism could make it go. If there is enough energy and the air continues to be unstable (a stable layer can stop this process), the growing cloud will become a thunderstorm.

Tornadoes develop from thunderstorm by complicated process that are not fully understood. In most cases the storm that produces a tornado is a supercell. These are especially powerful, long lived thunderstorms. They occur when thunderstorms encounter strong wind shear, where the wind speed and direction changes with altitude. The wind shear causes the storm's downdraft of rain cooler aid to fall away from the updraft that feeds the storm. As a result the storm can become stronger and last longer without cold air getting into and slowing or stopping the updraft. This is a critical aspect of most severe storms. However in a supercell the effect of the wind shear goes further. It actually causes the thunderstorm's updraft to start rotating, creating a mesocyclone. A downdraft within the storm can then cause the mesocyclone to stretch toward the ground, tighten, and intensify, forming a tornado. Most supercells do not produce tornadoes, however, and scientists are still not sure why some storms do produce tornado while others don't or why some produce stronger tornadoes than others.

Other storm type develop by different mechanisms, explanations of which can be found in the answers to other questions on this site.

Answer 8

Because tornadoes need a specific setup of conditions that occur more frequently in some area than in others.