How many tornadoes on average touch down in Tornado Alley each year?

Question

Any other info on the life and process of a tornado is also greatly appreciated!

Answer 1

A tornado is a violently rotating column of air which is in contact with both a cumulonimbus (or, in rare cases, cumulus) cloud base and the surface of the earth. Tornadoes can come in many sizes, but are typically in the form of a visible condensation funnel, with the narrow end touching the earth. Often, a cloud of debris encircles the lower portion of the funnel.

Most tornadoes have winds of 110 mph (175 km/h) or less, are approximately 250 feet (75 meters) across, and travel a few miles (several kilometers) before dissipating. However, some tornadoes can have winds of more than 300 mph (480 km/h), be more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 kilometers).[1][2][3]

Tornadoes have been observed on every continent except Antarctica; however, most of the world's tornadoes occur in the United States.[4] Other areas which commonly experience tornadoes include New Zealand, western and southeastern Australia, south-central Canada, northwestern and central Europe, Italy, south-central and eastern Asia, east-central South America, and Southern Africa.[5]

A tornado is not necessarily visible; however, the intense low pressure caused by the fast wind speeds and rapid rotation usually causes water vapor in the air to condense into a visible condensation funnel.

True tornadoes
Multiple vortex tornado
A multiple vortex tornado is a type of tornado in which two or more columns of spinning air rotate around a common center. Multivortex structure can occur in almost any circulation, however it is very often observed in intense tornadoes.

Satellite tornado
A satellite tornado is a term for a weaker tornado which forms very near a large, strong tornado contained within the same mesocyclone. The satellite tornado may appear to "orbit" the larger tornado (hence the name), giving the appearance of one, large multi-vortex tornado. However, a satellite tornado is a distinct funnel, and is much smaller than the main funnel.[3]

Waterspout
A waterspout is officially defined by the National Weather Service simply as a tornado over water. Amongst researchers, however, they are typically divided into two categories: "fair weather" waterspouts, and tornadic waterspouts.

"Fair weather" waterspouts are the less-severe (but far more common) variety, and are similar in dynamics to dust devils and landspouts.[13] They form from the bases of cumulus congestus (also called "convective cumulus") cloud towers in tropical and semitropical waters.[13] They have relatively weak winds (F0 on the Fujita scale), smooth laminar walls, and typically travel very slowly, if at all (since the cloud they are attached to is being formed by convective action instead of the interaction between colliding fronts).[13] They occur more commonly in the Florida Keys than anywhere on Earth.[14]
Tornadic waterspouts are more literally "tornadoes over water", and form the same way as tornadoes. A tornado which spawns in the traditional manner on land and later crosses into a body of water would also be considered a tornadic waterspout. Since they form from severe thunderstorms and have the capacity to be far more intense, faster, and longer-lived than their fair weather cousins, they are considered to be far more dangerous.
A third type, a winter waterspout, is an extremely rare meteorological phenomenon in which a vortex resembling that of a waterspout forms under the base of a snow squall. As opposed to warm season waterspouts, winter waterspouts form in temperatures of -18°C (0°F) or colder.

Landspout
A landspout is an unofficial term for a tornado not associated with a mesocyclone. The name stems from their characterization as essentially a "fair weather waterspout on land". They share most of the characteristics with their water-based brethren, including relative weakness, short lifespan, and a small, smooth condensation funnel which often does not reach the ground. Landspouts also create a distinctively laminar cloud of dust when they make contact with the ground, owing to their differing mechanics from true mesoform tornadoes. Though usually weaker than classic tornadoes, they still possess strong winds and can cause serious damage.[3][15]

Shape
Most tornadoes take on the appearance of a narrow funnel, a few hundred yards across, with a small cloud of debris near the ground. However, tornadoes can appear in many shapes and sizes.

Small, relatively weak landspouts may only be visible as a small swirl of dust on the ground. While the condensation funnel may not extend all the way to the ground, if associated surface winds are greater than 40 mph (64 km/h), the circulation is considered a tornado.[15] Large single-vortex tornadoes can look like large wedges stuck into the ground, and so are known as wedge tornadoes or wedges. A wedge can be so wide that it appears to be a block of dark clouds. Even experienced storm observers may not be able to tell the difference between a low-hanging cloud and a wedge tornado from a distance.[20]

Tornadoes in the dissipating stage can resemble narrow tubes or ropes, and often curl or twist into complex shapes. These tornadoes are said to be roping out, or becoming a rope tornado. Multiple-vortex tornadoes can appear as a family of swirls circling a common center, or may be completely obscured by condensation, dust, and debris, appearing to be a single funnel.[21]

In addition to these appearances, tornadoes may be obscured completely by rain or dust. These tornadoes are especially dangerous, as even experienced meteorologists might not spot them.[17]


[edit] Size
In the United States, an average tornado is around 500 feet (150 m) across, and stays on the ground for 5 miles (8 km).[17] While this is the average, there is an extremely wide range of tornado sizes, even for typical tornadoes. Weak tornadoes, or strong but dissipating tornadoes, can be exceedingly narrow, sometimes only a few feet across. In fact, a tornado was once reported to have a damage path only 7 feet (2 m) long.[17] On the other end of the spectrum, wedge tornadoes can have a damage path a mile (1.6 km) wide or more. A tornado which affected Hallam, Nebraska on May 22, 2004 was at one point 2.5 miles (4 km) wide at the ground.[2]

In terms of path length, the Tri-State Tornado, which affected parts of Missouri, Illinois, and Indiana on March 18, 1925, was officially on the ground continuously for 219 miles (352 km). Many tornadoes which appear to have path lengths of 100 miles or longer are actually a family of tornadoes which have formed in quick succession, however there is no substantial evidence that this occurred in the case of the Tri-State Tornado.[8] In fact, modern reanalysis of the path suggests that the tornado began 15 miles (24 km) further west than previously thought.[22]


[edit] Appearance
Tornadoes, depending on the environment in which they form, can have a wide range of colors. Tornadoes which form in a dry environment can be nearly invisible, marked only by swirling debris at the base of the funnel. Condensation funnels which pick up little or no debris can be gray to white. While travelling over a body of water as a waterspout, they can turn very white or even blue. Funnels which move slowly, ingesting a lot of debris and dirt, are usually darker, taking on the color of debris. Tornadoes in the Great Plains can turn red because of the reddish tint of the soil, and tornadoes in mountainous areas can travel over snow-covered ground, turning brilliantly white in the process.[17]


These are two photographs of the Waurika, Oklahoma tornado of May 30, 1976, taken at nearly the same time by two different photographers. In the top picture, the tornado is front-lit, with the sun behind the east-facing camera, so the funnel appears nearly white. In the lower image, where the camera is facing the opposite direction, the tornado is back-lit, with the sun behind the clouds.[23]Lighting conditions are also a major factor in the appearance of a tornado. A tornado which is "back-lit", or viewed with the sun behind it, will appear to be very dark. The same tornado, viewed with the sun at the observer's back, may appear gray or brilliant white. Tornadoes which occur near the time of sunset can be many different colors, appearing in hues of yellow, orange, and pink.[24][12]

Dust kicked up by the winds of the parent thunderstorm, heavy rain and hail, and the darkness of night are all factors which can reduce the visibility of tornadoes, making them "invisible", in essence. Tornadoes occurring in these conditions are especially dangerous, since only radar observations, or possibly the sound of an approaching tornado, serve as any warning to those in the storm's path. Fortunately most significant tornadoes form under the storm's rain-free base, or the area under the thunderstorm's updraft, where there is little or no rain. In addition, most tornadoes occur in the late afternoon, when the bright sun can penetrate even the thickest clouds.[8] Also, night-time tornadoes are often illuminated by frequent lightning. There is mounting evidence, including DOW mobile radar images and eyewitness accounts, which suggest that most tornadoes have a clear, calm center with extremely low pressure, akin to the eye found in tropical cyclones. This area would be clear (possibly full of dust), have relatively light winds, and be very dark, with the light blocked out by swirling debris on the outside of the tornado. Lightning is said to be the source of illumination for those who claim to have seen the interior of a tornado.[25][26][27]


[edit] Rotation
Tornadoes normally rotate cyclonically in direction (counterclockwise in the northern hemisphere, clockwise in the southern). While large-scale storms always rotate cyclonically due to the Coriolis effect, thunderstorms and tornadoes are so small that the direct influence of Coriolis effect is inconsequential, as demonstrated physically by the Rossby number. Supercells and tornadoes would rotate cyclonically even without the Coriolis effect, as evidenced by their doing so in numerical simulations which neglect the Coriolis component.[28][29] Low-level mesocyclones and tornadoes owe their rotation to complex processes within the supercell and ambient environment.[30]

Approximately 1% of tornadoes rotate in an anticyclonic direction. Typically, only landspouts and gustnados rotate anticyclonically, and usually only those which form on the anticyclonic shear side of the descending RFD in a cyclonic supercell.[31] However, on rare occasions, anticyclonic tornadoes form in association with the mesoanticyclone of an anticyclonic supercell, in the same manner as the typical cyclonic tornado, or as a companion tornado--either or a satellite tornado or associated with anticyclonic eddies within a supercell.[32]


[edit] Sound
The sound of a tornado is classically described as being similar to that of a speeding freight train rumbling in the distance.[33] A tornado's sound at close range, however, is different, due to direct effects of wind and debris. Storm chaser Tim Samaras described a tornado only 180 meters (600 ft) away as sounding "like a high-powered waterfall combined with a jet engine".[34] Most people residing inside their homes at the time a tornado strikes give a similar description.[35]

It averages about 1,200 tornadoes per year in Tornado Alley

Answer 2

The "official" location of Tornado Alley is undefined; but generally, it's considered to be in the Central United States from Northern Texas North through Nebraska and South Dakota.

"Tornado season" (the period of highest tornado activity) in this region runs from about March through May and the area experiences an average of about 1,000 tornadoes each year.

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Answer 3

Depending on the month, it can vary, even from state to state. but on average you can expect about 500 tornadoes per year. Some may not cause any damage at all, still others can wipe out an entire city, such as what happend sever weeks ago in Kansas.

Answer 4

Too many!!!!!!!!!!!!!! Scientists don't know exactly how tornadoes form, but that they usually occur in the United States when cool dry air from the north mixes with warm moist air from the south. Hope the future can help us broke the "myth of tornado".

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Answer 5

Id say about 30 average

Answer 6

I was wondering much the same question