The acute fury of a tornado is unmatched in nature. Yesterday, Greensburg, Kansas was destroyed by a tornado. Nine people died and rubble was 20 to 30 feet deep in places.
Nature has many ways to wreak violence and destruction: Earthquakes, volcanoes, droughts, floods, fires, blights, and plagues. Weather-wise, hurricanes and tornadoes vie for top spot. Under the right conditions, warm, damp air causes both: Hurricanes over warm, tropical oceans, and tornadoes over land. But just how do we determine which weather phenomenon is the more severe? Let’s do the math.
First let’s look at wind speed. Tornado winds have been measured at 320 miles per hour, nearly half the speed of sound and powerful enough to toss SUVs into trees. The strongest hurricanes have gusts that reach 200 miles per hour. Earth’s strongest wind is reserved for tornadoes.
Tornadoes aren’t very big in size, though; the largest span a mile or so in diameter. But they can travel hundreds of miles before dissipating. Hurricanes can be 100,000 times larger in area than tornadoes: often big enough to cover an entire country, and they also travel hundreds of miles before petering out. For total energy, hurricanes win.
Europe, Asia, and Australia all have tornadoes, but no country has a higher frequency – or severity – of tornadoes than the US, where 800 tornado reports a year is typical. Only a few hurricanes strike land each year and because their energy comes from the ocean and not the sky, they quickly lose their strength upon making landfall. Like a hive of bees, tornadoes may be small but their numbers make for an impressive impact.
The most damage ever caused by tornadoes – the Super Outbreak in April 1974 – caused over $600 million in damage. But that’s nothing compared to Hurricane Andrew, with $21 billion in insurance claims, or Katrina, with $60 billion. Hurricanes may be small in number, but have a 100 times higher capacity for destruction. And hurricanes kill more people than tornadoes, despite their lower frequency.
Just how do scientists measure tornado damage? They use the Fujita scale : F0 is the weakest and F5 the most violent. For hurricanes, it’s categories: 1 to 5 from weak to strong.
The legendary tornadoes of Kansas are memorialized in the Wizard of the Oz, filmed of course, in California. Hmm, you know, California hasn’t had an F3 tornado in 100 years. I know what you’re thinking – when was the last time there was an earthquake in Kansas? It happens that on November 9, 1968, a 5.3 magnitude earthquake was felt moderately throughout the eastern portion of Kansas. I guess no matter where we live, we all have to deal with nature.
That’s today’s math behind the news. I’m Larry Shiller.
Sources:
http://www.msnbc.msn.com/id/18502330/
http://mmem.spschools.org/grade5science/weather/hurricanevstornado.html
http://www.knowledgenews.net/science/tornadoes-hurricanes.htm
http://www.usatoday.com/money/economy/2005-09-09-katrina-damage_x.htm
http://www.nationalgeographic.com/forcesofnature/resources/famousforces.html
http://www.dvdtown.com/review/wizardofozthethree-disccollect/16508/3224/
