The most violent kind of storm;
an intense whirlwind of small diameter, extending downward from a convective
cloud in a severe thunderstorm, and
generally funnel-shaped cloud. Air rises rapidly in the outer region of
the funnel, but descends in its core, which is at very low pressure. The
funnel is visible owing to the formation of cloud droplets by expansional
cooling in this low pressure region. Very high winds spiral in toward the
core. These, and explosions due to the low pressure, account for the almost
total devastation and loss of life in the path of the tornado – which
itself might move at up to 200 m/s.
|The Cordell, Oklahoma, tornado of May 22, 1981. Source:
National Severe Storms Laboratory/University of Mississippi Tornado
Though generally rare, tornadoes occur worldwide, especially in the US and
Australia in spring and early summer. When they occur over water, they give
rise to a waterspouts.
PHENOMENA AND STRUCTURES