מדהים !!! טורנדו נדיר בישראל ליד חופי חיפה !!! 12.12.13 Tornado over water in Israel near Haifa 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. They are often referred to as twisters or cyclones,[1] although the word cyclone is used in meteorology, in a wider sense, to name any closed low pressure circulation. Tornadoes come in many shapes and sizes, but they are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds less than 110 miles per hour (177 km/h), are about 250 feet (76 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (483 km/h), stretch more than two miles (3.2 km) across, and stay on the ground for dozens of miles (more than 100 km).[2][3][4] Various types of tornadoes include the landspout, multiple vortex tornado, and waterspout. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud. 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. These spiraling columns of air frequently develop in tropical areas close to the equator, and are less common at high latitudes.[5] Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirls, and steam devil; downbursts are frequently confused with tornadoes, though their action is dissimilar. Tornadoes have been observed on every continent except Antarctica. However, the vast majority of tornadoes occur in the Tornado Alley region of the United States, although they can occur nearly anywhere in North America.[6] They also occasionally occur in south-central and eastern Asia, northern and east-central South America, Southern Africa, northwestern and southeast Europe, western and southeastern Australia, and New Zealand.[7] Tornadoes can be detected before or as they occur through the use of Pulse-Doppler radar by recognizing patterns in velocity and reflectivity data, such as hook echoes or debris balls, as well as by the efforts of storm spotters. There are several scales for rating the strength of tornadoes. The Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale. An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes.[8] Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and assign a rating.[9][10] Contents [hide] 1 Etymology 2 Definitions 2.1 Funnel cloud 2.2 Outbreaks and families 3 Characteristics 3.1 Size and shape 3.2 Appearance 3.3 Rotation 3.4 Sound and seismology 3.5 Electromagnetic, lightning, and other effects 4 Life cycle 4.1 Supercell relationship 4.2 Formation 4.3 Maturity 4.4 Dissipation 5 Types 5.1 Multiple vortex 5.2 Waterspout 5.3 Landspout 5.4 Similar circulations 5.4.1 Gustnado 5.4.2 Dust devil 5.4.3 Fire whirls and steam devils 6 Intensity and damage 7 Climatology 7.1 Associations with climate and climate change 8 Detection 8.1 Radar 8.2 Storm spotting 8.3 Visual evidence 9 Extremes 10 Safety 11 Myths and misconceptions 12 Ongoing research 13 Gallery 14 See also 15 References 16 Further reading 17 External links Etymology The word tornado is an altered form of the Spanish word tronada, which means "thunderstorm". This in turn was taken from the Latin tonare, meaning "to thunder". It most likely reached its present form through a combination of the Spanish tronada and tornar ("to turn"); however, this may be a folk etymology.[11][12] A tornado is also commonly referred to as a "twister", and is also sometimes referred to by the old-fashioned colloquial term cyclone.[13][14] The term "cyclone" is used as a synonym for "tornado" in the often-aired 1939 film The Wizard of Oz. The term "twister" is also used in that film, along with being the title of the 1996 tornado-related film Twister. Definitions 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".[15] For a vortex to be classified as a tornado, it must be in contact with both

• published: 13 Dec 2013
• views: 953