Hur många tornados finns
One tornado was reported to have a damage path only 7 feet 2. These tornadoes are said to be "roping out", or becoming a "rope tornado". Weak tornadoes, or strong yet dissipating tornadoes, can be exceedingly narrow, sometimes only a few feet or couple meters across. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud. The term is not precisely defined; for example, there is disagreement as to whether separate touchdowns of the same funnel constitute separate tornadoes.
When they rope out, the length of their funnel increases, which forces the winds within the funnel to weaken due to conservation of angular momentum. According to the Glossary of Meteorology , a funnel cloud is any rotating cloud pendant from a cumulus or cumulonimbus, and thus most tornadoes are included under this definition. Tornadoes in the dissipating stage can resemble narrow tubes or ropes, and often curl or twist into complex shapes.
The word tornado comes from the Spanish word tornado past participle of 'to turn', or 'to have turned', which comes from the Latin tonare 'to thunder'. This results in the formation of a visible funnel cloud or condensation funnel. The most extreme tornadoes can attain wind speeds of more than kilometers per hour mph , are more than 3 kilometers 2 mi in diameter, and stay on the ground for more than km 62 mi.
Most tornadoes have wind speeds less than kilometers per hour miles per hour , are about 80 meters feet across, and travel several kilometers a few miles before dissipating. If there is no break in activity, this is considered a tornado outbreak although the term "tornado outbreak" has various definitions. Multiple tornadoes produced by the same storm cell are referred to as a "tornado family".
It is often referred to as a twister , whirlwind or cyclone , [1] although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. These spiraling columns of air frequently develop in tropical areas close to the equator and are less common at high latitudes.
Small, relatively weak landspouts may be visible only as a small swirl of dust on the ground. An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud.
Various types of tornadoes include the multiple-vortex tornado , landspout , and waterspout.
Fråga forskarna: Kan Sverige också drabbas av tornador?
A tornado is a violently rotating column of air, in contact with the ground, either pendant from a cumuliform cloud or underneath a cumuliform cloud, and often but not always visible as a funnel cloud. Even experienced storm observers may not be able to tell the difference between a low-hanging cloud and a wedge tornado from a distance. Large tornadoes which appear at least as wide as their cloud-to-ground height can look like large wedges stuck into the ground, and so are known as "wedge tornadoes" or "wedges".
An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. There is some disagreement over the definition of a funnel cloud and a condensation funnel. A tornado is also commonly referred to as a "twister" or the old-fashioned colloquial term cyclone. Most tornadoes produce strong winds at the surface while the visible funnel is still above the ground, so it is difficult to discern the difference between a funnel cloud and a tornado from a distance.
Many, but not all major tornadoes are wedges. The Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale. Occasionally, a single storm will produce more than one tornado, either simultaneously or in succession.
Eldvirvlar och eldtornados
Tornadoes may be obscured completely by rain or dust. These tornadoes are especially dangerous, as even experienced meteorologists might not see them. There are several scales for rating the strength of tornadoes. Tornadoes occur most frequently in North America particularly in central and southeastern regions of the United States colloquially known as Tornado Alley ; the United States and Canada have by far the most tornadoes of any countries in the world.
A tornado is not necessarily visible; however, the intense low pressure caused by the high wind speeds as described by Bernoulli's principle and rapid rotation due to cyclostrophic balance usually cause water vapor in the air to condense into cloud droplets due to adiabatic cooling. A tornado that affected Hallam, Nebraska on May 22, , was up to 2.
Tornadoes often begin as funnel clouds with no associated strong winds at the surface, and not all funnel clouds evolve into tornadoes. In the United States, tornadoes are around feet m across on average. They are generally classified as non- supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes.
A wedge can be so wide that it appears to be a block of dark clouds, wider than the distance from the cloud base to the ground. A period of several successive days with tornado outbreaks in the same general area spawned by multiple weather systems is a tornado outbreak sequence, occasionally called an extended tornado outbreak.
Most tornadoes take on the appearance of a narrow funnel , a few hundred meters yards across, with a small cloud of debris near the ground.