A violently rotating column of air that extends from the base of a thunderstorm to the ground, capable of wind speeds exceeding 300 miles per hour in the most extreme cases. Tornadoes form most readily within supercell thunderstorms where strong vertical wind shear tilts a horizontally spinning air mass into a vertical funnel, and are ranked by the damage they cause on the Enhanced Fujita scale. The United States' Tornado Alley sees more tornadoes than anywhere else on Earth, owing to the collision of warm Gulf moisture with cold, dry continental air.
Facts
PeriodicityMost common in spring and least common in winter, though tornadoes can occur at any time of year when favorable conditions develop; spring and fall bring peaks of activity from stronger wind shear and atmospheric instability. 1 ScaleRated by the Fujita or Enhanced Fujita scale from F0/EF0 (weakest, damages trees but not substantial structures) to F5/EF5 (strongest, rips buildings off foundations); the TORRO scale runs T0 to T11. Most tornadoes have winds under 180 km/h and are about 80 meters wide; the most extreme exceed 480 km/h and can be over 3 kilometers in diameter. 1 Identification
Distinguishing AppearanceA rapidly rotating column of air extending from the ground to the base of a cumulonimbus or cumulus cloud, usually visible as a condensation funnel with a cloud of rotating debris and dust near the ground. 1 Connections
Associated With
A tornado is defined as a funnel cloud, or its associated ground-level circulation, that makes contact with the earth's surface; the two describe the same rotating column at different stages of one event.
Tropical cyclones commonly spawn tornadoes within their rainbands, particularly in the quadrant ahead and to the right of the storm's track, a well-documented secondary hazard of landfalling cyclones.
A wall cloud is the lowered, often rotating cloud base beneath a supercell thunderstorm from which many tornadoes descend, and is used operationally as a warning sign of tornado formation.
Demonstrated By
Source National Oceanic and Atmospheric Administration
Source National Oceanic and Atmospheric Administration
Sources
1. Tornado (Wikipedia)
WikipediaWikipedia 'Tornado', Climatology section
Tornadoes are most common in spring and least common in winter, but tornadoes can occur any time of year that favorable conditions occur.
Wikipedia 'Tornado', Rating section
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.
Wikipedia 'Tornado', lead section
Tornadoes are often (but not always) visible in the form of a condensation funnel originating from the cloud base, with a cloud of rotating debris and dust close to the ground.
View the Source National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric Administration- Demonstrated By: Grassland
- Demonstrated By: Great Plains
View the Source Reader Challenges (0)
No disputes yet. Spotted an error or a better source? Open the first one.
Sign in to dispute this or suggest a correction.