Tornado

From Glossary of Meteorology
Revision as of 05:10, 8 October 2013 by imported>Liss45 (→‎tornado)



tornado

A rotating column of air, in contact with the surface, pendant from a cumuliform cloud, and often visible as a funnel cloud and/or circulating debris/dust at the ground.

On a local scale, the tornado is the most intense of all atmospheric circulations. Its vortex usually rotates cyclonically (on rare occasions anticyclonically rotating tornadoes have been observed) with wind speeds as low as 30 m s-1 (67 mph) to as high as 135 m s-1 (300 mph), and is generally < 2 km (1.25 mi) in diameter. Tornado intensity is often estimated on the basis of wind damage using the Enhanced Fujita Scale; however, this estimate can be refined using other measurements, especially in the absence of damage indicators. Some tornadoes may also contain secondary vortices (also referred to as suction vortices, subvortices, multiple, and satellite vortices).Tornadoes have been observed on all continents except Antarctica but are most common in the United States, where the average number of reported tornadoes is roughly 1000 per year, with the majority of them on the central plains and in the southeastern states (see Tornado Alley). They can occur throughout the year at any time of day. In the central plains of the United States they are most frequent in spring during the late afternoon.

(See also Fujita Scale.)

term edited 8Oct2013


Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact permissions@ametsoc.org. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.