Tornadoes, with measured wind speeds of 125 m s−1 to perhaps 140 m s −1, are the most violent of atmospheric storms (Fig. 5.1). A tornado is defined here as a violently rotating, narrow column of air, averaging about 100 m in diameter, that extends to the ground from the interior of a cumulonimbus (or occasionally a cumulus congestus) cloud and appears as a condensation funnel pendant from cloud base and/or as a swirling cloud of dust and debris rising from the ground. Significant damage can occur at the ground even when the condensation funnel does not reach the surface. A condensation funnel associated with a tornadic vortex that fails to contact the ground is called a funnel cloud. A waterspout is a tornado over a body of water.

Tornadoes and Tornadic Storms

The definition of a tornado in the Glossary of Meteorology (Huschke 1959) begins with the following: "A violently rotating column of air, pendant from a cumulonimbus cloud, and nearly always observable as a 'funnel cloud' or tuba." This definition seems relatively straightforward, but in reality distinctions implied by the words we use tend to blur. Our ability to make distinctions among tornadic storm types and among tornadoes has been affected by three important developments since the last Tornado Symposium:

http://www.flame.org/~cdoswell/publications/Doswell&Burgess_93.pdf

Tornadoes and Toraadic Storms: a Review of Conceptual Models

Atmospheric hazards are the deadliest of all natural disasters in the United States (White and Haas 1975; Petak and Atkisson 1982). Local convective storm-induced severe weather and floods result in approximately 400 fatalities annually, with excessive heat and cold accounting for about 600 deaths and hurricanes for more than 30 fatalities each year (Riebsame et al. 1986). Convective storm mortality rates have stabilized, or even decreased, in the United States and other industrialized countries, but they have generally increased in developing nations.

Severe Local Storms Forecasting

Vortex phenomena in the united arab emirates

This model is an improved and adapted version of the mesome-teorological model described by Alpert P., Cohen A. and Neumann J., Hebrew University of Jerusalem (Alpert, 1980). Several simulations relative to a typical case of thermal breeze along the Belgian coast are presented, the results of which can be used as an input for the characteristic pollutant dispersion models of that region.

G. T. Meaden

Papers

Whirlwind formation at a sea breeze front