Bad weather always looks worse through a window.

- Tom Lehrer
 

Tornadoes are low pressure systems, and can generate wind velocities exceeding 200 mph.
Severe ones will flatten buildings (tornadoes have a special fondness for trailer parks),
uproot trees, and carry objects for 100s of feet to even miles from their spot of origin.
On 27 May 1997 several lines of storm clouds bearing multiple funnels crossed central Texas
with deadly results.  Here is a GOES-8 image of an advancing front.  Source: www.livescience.com NASA

	3 - 4 April 1974:  In 16 hours, 148 tornadoes were recorded across 13 states.  With ratings of F0 to F5, this tornado outbreak killed 330 people and injured almost 5,500.
	The most deadly single tornado in history was the Tri-state twister of 18 March 1925.  Moving across Missouri, Illinois and Indiana at speeds greater than 60 mph, this F5 tornado covered 219 miles and killed 695 people.
	A mile-wide tornado touched down near the town of Natchez, Mississippi, in 1840.  It was estimated that 48 people died on land, while 269 drowned in the Mississippi River in sinking boats and steamships.
	The biggest recorded tornado was nearly 2½ miles wide.  It occurred near Hallam, Nebraska on 22 May 2004.  But size does not necessarily imply strength!  Large tornadoes can have meagre wind speeds.
	By virtue of its land area and location, Oklahoma City has been hit by more tornadoes than any other city.  The worst of these was an F5 that struck on 3 May 1999, causing 36 deaths and a billion dollars worth of damage.

LiveScience / Source NOAA

Staying Safe

If a tornado strikes, the safest place is in a strong building - preferably in a basement or a small interior room.  The important thing is to get away from windows and put as many walls as possible between you and the outside.  Mobile homes do not provide adequate protection from a tornado.  If there are no secure buildings nearby, lie flat with your hands over your head in a ditch or depressed area.  Do not try to outrun a tornado in your car, experts say.

Source: www.livescience.com 22 March 2005

Billion Dollar Weather Disasters in the US

by Michael Schirber

Heat Danger

As dramatic as the recent hurricanes have been, it is perhaps surprising that droughts and heat waves cause the most damage and deaths.  In both 1980 and 1988, severe drought and heat ravaged the central and eastern parts of the country.  They were the only billion dollar events on the list for those 2 years, yet they alone made 1980 and 1988 the two costliest years on the list - $48 and $62 billion, respectively, in 2002 dollars.  These heat waves also were the deadliest weather or climate events of the study period - with estimated deaths due to heat stress approaching 10,000 in each case.

Source: www.livescience.com 20 January 2005

Taking the Twist Out of a Twister

A long spiral tornado approaches Union City, Oklahoma.
Source: www.livescience.com.  NOAA Photo Library

by Leonard David

Albuquerque, New Mexico - A blast of microwave energy beamed down from a space satellite could be used to tame the destructive nature of a tornado, a scientist said this week.  Such weather-watching duty might be assigned to future solar power stations that would circle Earth.

Each year, about 1,200 tornadoes are reported in the US, according to the American Meteorological Society.  An average of 55 people die annually as a result of twisters, and billions of dollars worth of property are destroyed or damaged.  Their extremely high winds propel debris, destroy homes, collapse buildings and overturn vehicles.  There is growing evidence that global warming may spawn increasing amounts of nasty weather, including tornadoes, at an even greater intensity in years to come.

But the tornado-nuking concept advocated here this week flies in the face of being at the mercy of Mother Nature’s fury.  Called a Thunderstorm Solar Power Satellite, the concept was presented at the Space 2000 Conference and Exposition on Engineering, Construction, Operations and Business in Space, sponsored by the American Society of Civil Engineers.  The proposal calls for beaming microwave energy into the cold, rainy downdraft of a thunderstorm where a tornado could originate.  That pulse of power would disrupt the convective flow needed to concentrate energy that forms a tornado, said Bernard Eastlund, president of Eastlund Scientific Enterprises Corporation, based in San Diego, California.  He has teamed up with Lyle Jenkins, a 37-year NASA veteran who now heads his own firm, Jenkins Enterprises in Houston, Texas.  The two researchers envision surgical strikes of microwave energy that could modify the temperature and fine structure of storm systems.

"We call it taming the tornado," Jenkins said.  "With just a little burst of microwave energy, we think we see a way to negate the trigger point in tornado creation.  We want to heat the cold rain.  By tailoring the beam, it can absorb the rain that is part of the tornado-making process."  Eastlund has looked at data provided by the Advanced Regional Prediction System at the Center for Analysis and Prediction of Storms Center at the University of Oklahoma.  These numerical simulation data were used to study the formation of conditions suitable for "tornado-genesis."  And he and Jenkins used them to see the effects of zapping an incipient storm with electromagnetic radiation beamed from a proposed Thunderstorm Solar Power Satellite.

Another aspect of their proposal could address the need for orbiting Doppler radar that could see tornado conditions forming.  These data would be fed into a tornado-stopping satellite, perhaps positioned in geosynchronous orbit above the areas most affected by severe weather.  By using a specially-tuned microwave pulse, rather than laser or infrared beams, that energy can be targeted within a storm’s interior, not through it or reflected away.  "You can’t wave your hands about this idea," Eastlund said.  "You’ve got to use real numerical modelling.  My research shows that by heating the falling rain, we can turn off the downdraft that drives a tornado."  More research is needed, he said, to further determine just how much energy would yield a knockout punch to a tornado on the brew.

But is it nice to fool with Mother Nature?  "This is a new science we’re talking about of weather modification...a new paradigm which seeks to mitigate these violent weather systems," Eastlund said.  "If it does prove possible to prevent tornadoes," Eastlund continued, "then systems could be envisioned in which severe storm phenomena such as hurricanes and typhoons are also modified in some beneficial fashion, and weather modification could be routine in the 21st century."

Source: www.space.com 3 March 2000

State-by-state Annual Tornado Average 1950 - 1995.  Credit: NCDC  Source: www.livescience.com

Also see:

	Wipeout (earlier in this section) - "At last the great shaggy end of the funnel hung directly overhead.  Everything was as still as death.  There was a strong gassy odour and it seemed that I could not breathe.  There was a screaming hissing sound coming directly from the end of the funnel.  I looked up and to my astonishment, I saw right into the heart of the funnel..."
	A Turn for the Worse - a diagram showing how tornados work.  It is somewhat slow to load but informative.
	'Tis the Season to Be Swept Away (the preceding page in this section) - The US is the country with the highest frequency of tornadoes - every state has recorded at least one in its past (although they are extremely rare in Alaska)...
	A Whirlwind Tour of Miami (the next page in this section) - A spectacular photo...
	Winds of Change (earlier in this section) - A full-fledged hurricane is a vast self-sustaining heat engine 100 times larger than a thunderstorm and 1,000 times more powerful than a tornado.  An ordinary summer afternoon thunderstorm has the energy equivalent of 13 Nagasaki-type atomic bombs.  Most hurricanes have at least 25,000 times that potential for destruction.  One storm in 1928 dropped 2,500 million tons of water on Puerto Rico in just two hours, but this was in fact only a fraction of its total capacity.  An average hurricane precipitates about 20,000 million tons of water a day, which represents the energy equivalent of half a million atom bombs...
	Hurricane (earlier in this section) - Hurricane activity runs in cycles, influenced by the ocean's salt content, currents and water temperature.  Their "busy period" is caused by a cyclical rise in salt content.  Higher salinity changes the ocean currents, which, in turn, makes water temperatures rise.  Hurricanes draw their strength from warm water...
	A Tremulous Motion and Preparing for the Inevitable (in the section on Wellington) - about Wellington earthquakes past and future.
	Enlightening Lightning (further in this section) - Lightning may seem relatively rare, but there are about a hundred flashes a second around the planet.  Ground strikes almost always create currents in the surrounding soil...

For pages on natural disasters - including the above-mentioned lightning strikes, volcanoes and hurricanes but also global warming and more - as well as satellite photos and some great pictures of trees, clicking the "Up" button immediately below takes you to the Table of Contents page for this Environment section.