Finger Of God - Tornados

What Is A Tornado?

"A violently rotating column of air, in contact with the ground, either pendant from a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud. " -American Meteorological Society glossary of terms.

Things to remember about this definition:

1) A tornado is air. What hurts or kills people is the debris swirling around a tornado.

2) A tornado is by definition not necessarily visible. Rotating air in contact with the ground usually becomes visible due to the dirt it picks up and/or the condensation of water in the air forming a funnel like cloud giving the tornado it's visible appearance.

3) A tornado is by definition in contact with the ground.

In fact, if it is not touching the ground, it is often referred to as a funnel cloud. However, that may be a misleading term.

Tornadoes can last for seconds or close to an hour, though most last less than 10 minutes. Most tornadoes in the U.S. form between March and August, when atmospheric conditions are most favorable for the severe thunderstorms that produce tornadoes. However, the tornado season never truly ends. In fact, winter tornadoes are not all that uncommon, but they usually occur in the Southern US where it is much warmer than say...Minnesota. In Iowa however, there has been a tornado recorded in the state in every month of the year. So although January tornadoes are rare in the Midwest, they have occurred.

It often appears as if a tornado comes down from the thunderstorm, first as a funnel cloud and then making contact with the ground. But this is a deceiving observation. As the rotation is already in contact with the ground and not coming down from the thunderstorm. Initially the vortex is not intense enough to pick up dirt or form that classic tornado condensation cloud, but nevertheless it is in contact with the ground. But as the vortex tightens (like the figure skater pulling their arms inward and spinning faster) water condenses near the cloud base and that's why the classic looking funnel cloud forms out of the thunderstorm first.

Webster County, NE. Doug Raflik

Waterspout over the West Coast of Florida. Jürg Beeli. 1973 Union City, Oklahoma

Enhanced F Scale for Tornado Damage

An update to the the original F-scale by a team of meteorologists and wind engineers, to be implemented in the U.S. on 1 February 2007.

IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale still is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to the 28 indicators listed below. These estimates vary with height and exposure. Important: The 3 second gust is not the same wind as in standard surface observations. Standard measurements are taken by weather stations in open exposures, using a directly measured, "one minute mile" speed.

Enhanced F Scale Damage Indicators

	South Hams, England,UK
Slapton, England, UK	between Dartmouth and Brixham, England, UK
near Totnes, England, UK	Kingsbridge, England, UK
East Allington, England, UK
	Sacramento, California 2005
Tornado near Casino, NSW, Australia	Harper, Kansas