WxTorn01a_12 WxTorn01a_22 WxTorn02a_27 WxTorn2626_052 WxTorn2626_055 WxTorn2626_059 WxTorn04d_13 WxTorn04b_35 WxTorn2626_096 PREV    NEXT

Home Gallery Information Search Feedback Photographer Copyright Weather Gallery (Page 5 of 6) Cloud basics Cloud-specifics Optical Phenomenon Supercell Thunderstorms Tornadoes Lightning Photo Tips © Gregory Thompson All rights reserved

Tornadoes:
As defined by the Glossary of Meteorology (Huschke 1959), a tornado is "a violently rotating column of air, pendant from a cumulonimbus cloud, and nearly always observable as a funnel cloud or tuba". More recently, researchers are adding the qualifier that the violently rotating column of air be in contact with the ground otherwise, it is referred to as a funnel cloud. A good example of the distinction is made using this photograph which depicts an obvious funnel cloud but much less obvious dust column and very small debris evident at the ground. This is a weak tornado. Many researchers have discussed a more thorough and updated definition of tornadoes for years; if interested, I advise you read Dr. Chuck Doswell's exhaustive discussion on this topic.
 
Tornado Safety:
The safest place to be during a tornado is underground in a storm shelter. Few have access to such shelter so any location below ground level is advised, like a basement or crawl space. If you cannot get below ground then interior closets and bathrooms are the next best place because of the better reinforcing wall structures. If you have a mobile home, you are likely in more danger by staying inside the home than by leaving it completely. If you are caught outdoors during a tornado, try to get indoors following the above advice unless your only option is a mobile home. If no indoor/underground options exist, then you are safest when you are lying as low as possible in a ditch. Contrary to popular belief, you are not safe "under the girders" of a road overpass. Multiple people died in this manner on 3 May 1999 in Oklahoma City, OK. A strong tornado IS capable of destroying road overpasses completely! You are also not safe in a car trying to out-run a tornado; instead you are better off lying flat in a ditch. This last statement comes with one possible exception: if you clearly know the movement of a tornado and have ample time to drive in a direction perpendicular to a tornado's movement, then you may be safer driving away from it. Consider how difficult this could be with very clouded judgement caused by such impending danger. A more comprehensive web site with safety information is the Storm Prediction Center safety page.
 
Additional Tornado Info:
I could not begin to duplicate the incredible quantity of information on tornadoes on this web site. I mostly want people to read the Safety section. An internet search on tornadoes is likely to produce thousands of web pages - go for it. Meanwhile, for a very enjoyable coffee-table book on chasing tornadoes plus a lot more, I highly recommend Howie Bluestein's well-written and beautifully-illustrated book: Tornado Alley. I borrow these few sentences to illustrate some questions still perplexing the best researchers I know:
The source of rotation in some tornadoes appears to be preexisting vortices near the ground above where convective storms are growing; in others, the source seems to be linked to the mesocyclone. Does the mesocyclone itself descend to the ground and intensify to become the tornado, or does it trigger events near the ground that create tornadoes from other sources of rotation? Can it do both?
Tornado Chases:
Every year since 1991, I chase storms mostly in Colorado and mostly between the months of April and July. During my CSU graduate student days, I chased perhaps twenty times per season. In recent years, I chase approximately half that number partly because I've learned a lot from busts and am pickier about the necessary conditions for tornadic storms and partly because my family and work responsibilities have increased. Below are links to particularly memorable tornado chases. Within these links are discussion of the day's weather data. See what tools professional atmospheric scientists use to make a forecast of tornadoes anywhere from one to eight (or more) hours in advance. The list will certainly grow in 2000 since I will actively collect the data in realtime and post summaries here instead of my work web areas.

• 30 May 1996 near Akron, Colorado
• Awaiting the 2000 season