Thunderstorm Produced by a cumulonimbus cloud, it is a microscale event of relatively short duration characterized by thunder, lightning, gusty surface winds, turbulance, hail, icing, precipitation, moderate to extreme up and downdrafts, and under the most severe conditions, tornadoes. Tornado A violently rotating column of air in contact with and extending between a convective cloud and the surface of the earth. It is the most destructive of all storm-scale atmospheric phenomena. They can occur anywhere in the world given the right conditions, but are most frequent in the United States in an area bounded by the Rockies on the west and the Appalachains in the east. The irregular and instantaneous motions of air that is made up of a number of small eddies that travel in the great air current.
Atmospheric turbulence is caused by random fluctuations in the wind flow.
It can be caused by thermal or convective currents, differences in terrain and wind speed, along a frontal zone, or variation in temperature and pressure. Twister A slang term used in the United States for a tornado. Warning A forcast issued when sever weather has developed, is already occuring and reported, or is detected on radar. Warnings state a particular hazard of imminent danger, such as tornadoes, severe thunderstorms, flash and river floods, winter storms, heavy snows, etc. A forcast issued well in advance of a severe weather event to alert the public of the possibility of a particular hazard, such as tornadoes, severe thunderstorms, flash and river floods, winter storms, heavy snows, etc.