Tens of thousands of New Orleans residents are fleeing the below-sea-level city today before Hurricane Ivan blows through town. This hurricane season has been especially hard (just ask a Floridian). And it could get worse. More tropical storms are brewing offshore.
Nature has a thousand ways to kill you. Wind, earthquake, volcano, drought, flood, fire--you name the place and choose the form of destruction, and nature has an unequivocal way to show who's boss.
In North America, warm weather brings disaster by air--by hurricane and tornado. Tornadoes can strike anytime, but occur most frequently in spring and early summer. Hurricane season picks up where tornadoes leave off, running June through November. Both are awesome forms of windpower that represent nature at its fiercest.
But which is meaner? Which is deadlier? Which is the baddest atmospheric force on Earth? We've matched these two forces head-to-head and broken them down with some scientific facts to see which is the true king of disaster in the sky.
Wind Speed
Tornadoes - Packed into tight, swirling spirals, the winds of the most powerful (F5) tornadoes can reach speeds approaching 320 miles (515 km) per hour--the most violent winds on Earth. Just how fast is 320 miles per hour? It's faster than a Formula One race car, faster than many airplanes can fly, and almost half the speed of sound. At that speed, wind can fling cars across football fields and reduce the sturdiest house to rubble. The majority of tornadoes, however, rage at less than 200 miles (322 km) per hour. That's still fast enough to uproot trees and destroy your average mobile home.
Hurricanes - A stiff breeze of, say, 30 miles (48 km) per hour will blow your trusty umbrella inside out, sweep the hat off your head, and make it hard to walk upwind. Now triple that speed, and you've got a hurricane on your hands--a weak one. If you wanted a strong hurricane, you'd have to whip up sustained winds of over 150 miles (241 km) per hour, with gusts that top 200 miles (322 km) per hour. At hurricane wind speeds, loose debris becomes a barrage of flying missiles. Even if you could stand up straight in a hurricane wind, it wouldn't be a good idea.
Advantage: Tornadoes.
It's all in the numbers. Even the most severe hurricanes make it only halfway up the tornado intensity scale. There's no wind on Earth stronger than the wind inside a tornado.
Size
Tornadoes - Tornadoes are relatively small as atmospheric phenomena go. Funnel width at ground-point usually ranges from a few dozen to several hundred yards across. Some tornadoes reach more impressive widths--more than a mile (1.6 km) at ground-point. Yet because tornadoes move rapidly along the ground, they can cause damage over a larger area than their size might suggest. Larger, longer-lived tornadoes can cut a swath of destruction hundreds of miles long.
Hurricanes - Hurricanes are huge; they can cover entire states. One look at a hurricane through a satellite photo shows just how big they can be. The average hurricane is 200 to 300 miles (322 to 483 km) in diameter, and massive hurricanes can span 700 miles (1,127 km) or more. The size of a hurricane, however, is not directly related to its wind speed or destructive force. Relatively small ones can pack an incredible punch, while much larger ones can be relatively mild.
Advantage: Hurricanes.
Tornadoes may dominate the sky, but hurricanes swallow it whole.
Frequency and Range
Tornadoes - Tornadoes tend to occur over flat terrain, but can travel across mountains and form over water. In 1997, a tornado even passed through the heart of downtown Miami. Although they're found in places like India, Europe, and Australia, tornadoes are most common--and most powerful--in the United States. Tornadoes can form year-round, but most occur in a "tornado season" of March through May and through the summer in more northern states. A typical year will see close to 800 tornado reports in the U.S. and a higher number worldwide.
Hurricanes - Because they require the tropical ocean to maintain their intensity, hurricanes quickly lose their strength when they make landfall or move into cooler climates. This greatly limits the number of places they can strike. The same factors that spawn hurricanes also limit their frequency. Like tornadoes, hurricanes tend to strike in season, which in the Atlantic is from June through November. On average, only a dozen hurricanes a year are spawned there, and many of those never strike populated areas.
Advantage: Tornadoes.
What they lack in size, they more than make up for in frequency, with some years having 100 times as many reported tornadoes as hurricanes. And they can get around the country, too.
Damage
Tornadoes - Tornadoes pack quite a wallop, and when they strike near populated areas, the damage can be severe. Most damage is localized and random. Tornadoes are notorious for destroying houses on one side of the street while leaving those on the other untouched. The biggest tornado outbreak in the last century--the "Super Outbreak" of April 3-4, 1974--spawned 148 tornadoes across 13 states and caused damage in excess of $600 million, $100 million of which resulted from a massive tornado that destroyed half the town of Xenia, Ohio.
Hurricanes - Because of their longevity and immense size, hurricanes can wreak tremendous havoc. The combined effects of wind, rain, and surf can destroy homes, erode seashores, and flood entire cities. Luckily, most hurricanes spend the majority of their lives in the open ocean. How much damage a hurricane does is determined as much by when, where, and how it strikes coastal areas as by the magnitude of the storm itself. When Hurricane Andrew struck both south Florida and Louisiana in 1992, it caused total damage estimated at $36 billion.
Advantage: Hurricanes.
Tornadoes pack a solid punch, but hurricanes deliver a knockout combination of wind and water that tornadoes simply cannot match.
Deaths
Tornadoes - Despite greatly improved weather tracking and warning systems, tornadoes still kill an average of 100 people in the United States each year. Although they can lift humans into the air and hurl them long distances, flying debris and collapsing buildings cause most deaths. The worst event on record is the Great Tri-State Tornado of March 18, 1925, a mile-wide monster that tore across 219 miles (352 km) of Missouri, Illinois, and Indiana, killing 695 people, injuring 2,207, and destroying more than 15,000 homes.
Hurricanes - Improved weather tracking and warning systems have greatly reduced the number of deaths caused by hurricanes. The 1928 hurricane that struck Lake Okeechobee in Florida killed 1,836 people. Estimates from earlier storms point to several that killed even more. Even with modern satellite tracking and early evacuation plans, Hurricane Floyd caused 56 deaths in 1999. And not every place has such modern tools. In 1991, a typhoon (as hurricanes are called in the western Pacific and Indian oceans) struck low-lying sections of Bangladesh and killed almost 140,000 people.
Advantage: Hurricanes.
Hurricanes kill more, especially worldwide, even if they do it less often than tornadoes. (Yet neither storm comes close to nature's worst killers: flooding and drought.)
Power
Tornadoes - Yard for yard, tornadoes pack the most destructive force of any atmospheric phenomenon, possessing a pinpoint violence unmatched by any other force of nature. In fact, a good-sized twister releases energy at a rate equal to that of two large nuclear reactors. Don't be too impressed, though. The "supercell" thunderstorms that spawn tornadoes typically have a total energy output thousands of times greater than that.
Hurricanes - The sheer size of a hurricane allows it to unleash massive amounts of destructive power on anything unfortunate enough to be engulfed by it. And unlike tornadoes, which rarely last for more than an hour, a hurricane can rage for days. All of that adds up to staggering energy levels. By some calculations, a typical hurricane generates power at a rate equal to that of half of the electrical production of the entire world at any given time.
Advantage: Hurricanes.
Even though tornadoes produce an impressive display of ground-churning power, they lack hurricanes' size and stamina. If that's not enough to convince you, consider this: Hurricanes are so powerful that they can spin off tornadoes of their own.
Intangibles
Tornadoes - In spite of their destructiveness, tornadoes fascinate. Every year, hundreds of people go storm-chasing across the countryside in an effort to measure, document, or simply witness tornadoes' breathtaking power. For whatever reason, the sight of a funnel cloud in the sky often sends folks running for their cameras before they run for their lives.
Hurricanes - Though they certainly goose the Weather Channel's ratings, hurricanes don't have the cinematic, visual appeal of tornadoes, probably because they're just too large to be seen in their entirety. It wasn't until humans could look down on these storms from space that their magnitude could be appreciated. The experience of being in one, however, leaves little to the imagination.
Advantage: Tornadoes.
They've got style, they're quirky, and they're quite photogenic. All they need now is an agent. In fact, the movie Twister grabbed $242 million in box office receipts in 1996 (though U.S. tornadoes caused more than $716 million in estimated damage the same year).
And the Winner Is . . . Hurricanes.
Both hurricanes and tornadoes are amazing, they're both deadly, and they're both destructive. But in this case, size does matter. Tornadoes may be more visually spectacular, and evoke more popular excitement and interest, but the sheer magnitude and power of the hurricane is unmatched among nature's skyborne forces.
Want to learn more?
Track Ivan's march with the latest radar image
http://www.srh.noaa.gov/radar/latest/DS.p38cr/si.klix.shtml
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