Facts about Tornado

On the contrary, a highway overpass is a dangerous place during a tornado.

Worldwide, most tornadoes occur in the late afternoon, between 3 and 7 P.M. local time, with a peak near 5 P.M. However, destructive tornadoes can occur at any time of day.

Tornadoes emit widely on the acoustics spectrum and the sounds are cased by multiple mechanisms.

Strong tornadoes also occasionally occur in northern Mexico.

The winds of the tornado vortex and of constituent turbulent eddies, as well as airflow interaction with the surface and debris, contribute to the sounds.

A violent tornado can destroy a house whether its windows are open or closed.

The Gainesville Tornado of 1936, one of the deadliest tornadoes in history, occurred at 8:30 A.M. local time.

The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes.

Scientists still do not know the exact mechanisms by which most tornadoes form, and occasional tornadoes still strike without a tornado warning being issued, especially in under-developed countries.

A tornado was once reported to have a damage path only 7 feet (2 m) long.

Supercells and tornadoes rotate cyclonically in numerical simulations even when the Coriolis effect is neglected.

One of the most persistent myths associated with tornadoes is that opening windows will lessen the damage caused by the tornado.

Authorities such as the Storm Prediction Center advise having a tornado plan.

Tornadoes have been observed on every continent except Antarctica.

Tornado occurrence is highly dependent on the time of day, because of solar heating.

Tornadoes which occur near the time of sunset can be many different colors, appearing in hues of yellow, orange, and pink.

By comparison, during the same tornado outbreak, more than 2000 homes were completely destroyed, with another 7000 damaged, and yet only a few dozen people died in their homes.

Only wall clouds that rotate spawn tornadoes, and usually precede the tornado by five to thirty minutes.

Storm spotters are needed because radar systems such as NEXRAD do not detect a tornado; only indications of one.

On the other end of the spectrum, wedge tornadoes can have a damage path a mile (1.6 km) wide or more.

Most tornadoes take on the appearance of a narrow funnel, a few hundred yards (a few hundred meters) across, with a small cloud of debris near the ground.

A tornado which is "back-lit" (viewed with the sun behind it) appears very dark.

The safest place is the side or corner of an underground room opposite the tornado's direction of approach (usually the northeast corner), or the central-most room on the lowest floor.

More often than not, overall cloud-to-ground (CG) lightning activity decreases as a tornado reaches the surface and returns to the baseline level when the tornado lifts.

Not only did this outbreak feature an incredible 148 tornadoes in only 18 hours, but an unprecedented number of them were violent; six were of F5 intensity, and twenty-four F4.

Under the updraft is a rain-free base, and the next step of tornadogenesis is the formation of a rotating wall cloud.

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.

Intense tornadoes have been observed forming simultaneously with a mesocyclone aloft (rather than succeeding mesocyclogenesis) and some intense tornadoes have occurred without a mid-level mesocyclone.

Some countries have meteorological agencies which distribute tornado forecasts and increase levels of alert of a possible tornado (such as tornado watches and warnings in the United States and Canada).

The most extreme tornado in recorded history was the Tri-State Tornado which roared through parts of Missouri, Illinois, and Indiana on March 18, 1925.

Finally, there are areas which people believe to be protected from tornadoes, whether by a major river, a hill or mountain, or even protected by "spirits."

The United States has the most tornadoes of any country, about four times more than estimated in all of Europe, not including waterspouts.

Electromagnetics and lightning have little to nothing to do directly with what drives tornadoes (tornadoes are basically a thermodynamic phenomenon), though there are likely connections with the storm and environment affecting both phenomena.

Lightning is said to be the source of illumination for those who claim to have seen the interior of a tornado.

Various sounds of tornadoes have been reported throughout time, mostly related to familiar sounds for the witness and generally some variation of a whooshing roar.

Many tornadoes are not audible from much distance; the nature and propagation distance of the audible sound depends on atmospheric conditions and topography.

Tornadoes normally rotate cyclonically in direction (counterclockwise in the northern hemisphere, clockwise in the southern).

When a tornado warning is issued, going to a basement or an interior first-floor room of a sturdy building greatly increases chances of survival.

Reliably predicting tornado intensity and longevity remains a problem, as do details affecting characteristics of a tornado during its life cycle and tornadolysis.

Barring a low-level boundary, tornadogenesis is highly unlikely unless a rear flank downdraft occurs, which is usually visibly evidenced by evaporation of cloud adjacent to a corner of a wall cloud.

Most tornadoes have wind speeds of 110 miles per hour (mph) (175 kilometers per hour (km/h)) or less, are approximately 250 feet (75 meters (m)) across, and travel a few miles (several kilometers) before dissipating.

The vast majority of intense tornadoes occur with a wall cloud on the backside of a supercell.

A tornado is a violently rotating column of air that is in contact with the base of a cumulonimbus cloud (or occasionally, a cumulus cloud) and the Earth's surface.

Tornadoes can have a wide range of colors, depending on the environment in which they form.

In Canada, weather forecasts and warnings, including tornadoes, are produced by the Meteorological Service of Canada, a division of Environment Canada.

Storms which produce tornadoes can feature intense updrafts (sometimes exceeding 150 mph, 240 km/h).

Debris from a tornado can be lofted into the parent storm and carried a very long distance.

The highest wind speed ever measured in a tornado, which is also the highest wind speed ever recorded on the planet, is 301 ± 20 mph (484 ± 32 km/h) in the F5 Moore, Oklahoma tornado.

Tornadoes have been known to cross major rivers, climb mountains, and affect valleys.

Initially, the tornado has a good source of warm, moist inflow to power it, so it grows until it reaches the mature stage.

Tornadoes often develop from a class of thunderstorms known as supercells.

Meanwhile, the RFD, now an area of cool surface winds, begins to wrap around the tornado, cutting off the inflow of warm air which feeds the tornado.

The association with track length and duration also varies, although longer track tornadoes tend to be stronger.

Another commonly held belief is that highway overpasses provide adequate shelter from tornadoes.

Approximately one percent of tornadoes rotate in an anticyclonic direction.

Meteorology is a relatively young science and the study of tornadoes even more so.

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 1953 it was confirmed that hook echoes are associated with tornadoes.

Just prior to the expected onset of an organized severe weather threat, SPC issues severe thunderstorm and tornado watches, in collaboration with local National Weather Service offices.

Outside the United States, areas in south-central Asia, and perhaps portions of southeastern South America and southern Africa, violent tornadoes are extremely rare.

Before the 1950s, the only method of detecting a tornado was by someone seeing it on the ground.

Most tornadoes from supercells follow a recognizable life cycle.

The deadliest tornado in world history was the Daultipur-Salturia Tornado in Bangladesh on April 26, 1989, killing approximately 1300 people.

When severe weather is anticipated, local weather service offices request that these spotters look out for severe weather, and report any tornadoes immediately, so that the office can issue a timely warning.

Most intense tornadoes (EF3 to EF5 on the Enhanced Fujita Scale) develop from supercells.

More than 300 people, possibly as many as 330, were killed by tornadoes during this outbreak.

Temperature tends to decrease and moisture content to increase in the immediate vicinity of a tornado.

Rigorous attempts to warn of tornadoes began in the United States in the mid-twentieth century.

Tornadoes can also be caused by landfalling tropical cyclones, which tend to occur in the late summer and autumn.

Tornadoes may also occur without wall clouds, under flanking lines, and on the leading edge.

Tornadoes are also commonly referred to as twisters.

A few significant tornadoes occur annually in Europe, Asia, southern Africa, and southeastern South America, respectively.

Other rich areas of research are tornadoes associated with mesovortices within linear thunderstorm structures and within tropical cyclones.

The first public tornado warnings were issued in 1950 and the first tornado watches and convective outlooks in 1952.

Warnings are issued by local National Weather Service offices when a severe thunderstorm or tornado is occurring or imminent.

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.

Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes.

Tornadoes also produce a detectable seismic signature, and research continues on isolating it and understanding the process.

Usually, the funnel cloud becomes a tornado within minutes of the RFD reaching the ground.

The European Union founded a project in 2002 called the European Severe Storms virtual Laboratory, or ESSL, which is meant to fully document tornado occurrence across the continent.

The rate of occurrence drops off quickly with increasing strength—less than one percent are violent tornadoes, stronger than EF4, T8.

During this stage the shape of the tornado becomes highly influenced by the winds of the parent storm, and can be blown into fantastic patterns.

The same tornado, viewed with the sun at the observer's back, may appear gray or brilliant white.

Regardless of the validity of the explosion claim, time would be better spent seeking shelter before a tornado than opening windows.

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.

Occasionally, the old (occluded) mesocyclone and the new mesocyclone produce a tornado at the same time.

Many tornadoes are not audible from much distance; the nature and propagation distance of the audible sound depends on atmospheric conditions and topography.

By recognizing these radar signatures, meteorologists could detect thunderstorms likely producing tornadoes from dozens of miles away.

Tornadoes come in many sizes, but they typically take the form of a visible condensation funnel whose narrow end touches the Earth and is often encircled by a cloud of debris.

A large portion of these tornadoes form in an area of the central United States known as Tornado Alley.

Weak tornadoes, or strong but dissipating tornadoes, can be exceedingly narrow, sometimes only a few feet across.

The word "tornado" is an altered form of the Spanish word tronada, which means "thunderstorm."

Lighting conditions are a major factor in the appearance of a tornado.

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.

Tornadoes in the dissipating stage can resemble narrow tubes or ropes, and often curl or twist into complex shapes.

Highway overpasses are extremely bad shelter during tornadoes (see next section).

Large single-vortex tornadoes can look like large wedges stuck into the ground, and so are known as wedge tornadoes or wedges.

Research programs, including field projects such as VORTEX, deployment of TOTO (the TOtable Tornado Observatory), Doppler On Wheels (DOW), and dozens of other programs, hope to solve many questions that still plague meteorologists.

A tornado that affected Hallam, Nebraska on May 22, 2004 was at one point 2.5 miles (4 km) wide at the ground.

An EF0 tornado will likely damage trees but not substantial structures, whereas an EF5 tornado can rip buildings off their foundations leaving them bare and even deform large skyscrapers.

Tornadogenesis is most likely at the interface of the updraft and front flank downdraft, and requires a balance between the outflow and inflow.

Often, news of a tornado would reach a local weather office after the storm.

Low-level mesocyclones and tornadoes owe their rotation to complex processes within the supercell and ambient environment.

In 1953 it was confirmed that hook echoes are associated with tornadoes.

The word "tornado" is an altered form of the Spanish word tronada, which means "thunderstorm."

Today, most developed countries have a network of weather radars, which remains the main method of detecting signatures likely associated with tornadoes.

Tornadoes emit on the electromagnetic spectrum, for example, with sferics and E-field effects detected.

Intense tornadoes have been observed forming simultaneously with a mesocyclone aloft (rather than succeeding mesocyclogenesis) and some intense tornadoes have occurred without a mid-level mesocyclone.