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The True Face of Hurricanes
Bijal Trivedi - National Geographic Channel Meteorologist Josh Wurman is a storm chaser of the extreme variety. He doesn't just want a close encounter, he wants to get in a hurricane's path and experience the chaos as the swirling mass hits the land and travels directly over him. Only then can he get the measurements he needs to understand the complicated inner workings of the storm.
How and why some structures are demolished by hurricanes while others nearby remain untouched has long mystified scientists. It's a pattern of destruction associated with tornados, but Wurman doesn't believe tornados are at work near the eye of the hurricane. Now Wurman, director of the Boulder-based Center for Severe Weather Research, wants to crack the puzzle by conducting a daring experiment—driving himself and his instruments directly in the path of a fierce hurricane's eye... that of hurricane Frances.
Wurman's instrument of choice is a mobile Doppler radar that sits on a truck reinforced to withstand the violence of a hurricane. The Doppler on Wheels, DOW as it is known, can peer into the hurricane and see features as small as 40 feet across—revealing wind streaks, gusts and other potentially destructive features. He is particularly interested in the anatomy of the winds surrounding the eye of Frances; this circular wall of wind is the most powerful region of the hurricane, and the least understood.
For National Geographic Explorer's The True Face of Hurricanes, filmmakers deployed 13 camera teams to Florida to cover the 2004 hurricane season. They captured the drama that unfolds as these massive storms reach the shore. One team followed Wurman into the heart of the hurricane. Another joined the Air Force pilots who flew into the eye. A third team was assigned to cover Max Mayfield, the director of the National Hurricane Center in Miami, as he followed the progress of hurricane Frances and triggered the biggest evacuation in Florida history, causing two and a half million people to flee the coasts. Other teams documented the frantic and emotional departure of families as they abandoned their homes and later returned to salvage the remnants. Some camera crews even battened down the hatches with local families to ride out the storm.
Four hurricanes slammed into Florida in 2004—first Charley, then Frances, Ivan and Jeanne—making it the costliest and most destructive season on record. Charley, a category four storm, made landfall in Punta Gorda on August 13th causing 22 deaths and an estimated $6.8 billion in damage. Then Frances battered the state for 30 hours in early September making landfall twice, killing 15 people and causing 2.5 billion in damages. Ivan wrought a path of destruction through the Caribbean before hitting the shores of Alabama on September 15. Jeanne devastated Haiti—killing more than 1,500—on September 17. By the time it reached Florida it had diminished to a category two storm but still caused the deaths of six people.
Hurricanes are rated from one to five on the Saffir-Simpson scale, which ranks them based on wind speed. The rank provides an indicator of destructive potential and the amount of flooding expected from the storm surge. A category one hurricane is accompanied by 74-95 mile/hour winds and storm surges generally four to five feet above normal. There is little damage to building structures, and destruction is mostly limited to mobile homes, shrubbery, and trees. A category five brings winds greater than 155 mile/hour and storm surges more than 18 feet above normal. The winds strip roofs—in some cases blowing away the entire buildings. All shrubs, trees, and signs are blown down and flooding is widespread.
The deadliest hurricane in US history was a category four storm that killed 8,000 people when it hit Galveston, Texas in 1900. Back then meteorologists had only a vague idea of a hurricane's position, from ships or islands that the storms just passed. Narrowing down the location became easier with airplanes but it wasn't until man conquered space that hurricanes could be seen in their entirety. Satellites can now reveal everything from air pressure to temperature to humidity.
Although residents today have warnings several days before a hurricane hits, meteorologists still struggle to precisely predict the path and intensity of storms that are sometimes larger than the state of Texas. Hurricane Charlie was expected to pack a category two punch but instead made landfall at 145 miles per hour—just 10 miles/hour shy of the most destructive category five hurricane. The error was due in part to a lack of measurements of water temperature, rapidly morphing atmospheric conditions and a poor grasp of the physics at work in the hurricanes heart.
How the winds behave has profound implications for the amount of damage they will cause. To examine hurricane Frances's internal anatomy—it's eye—Wurman used two mobile Dopplers to shoot radio waves at the hurricane from two different locations. Like an x-ray revealing the skeleton, the radar sees through the torrents of rain, churning cloud and debris to reveal the violent forces at play in the interior.
The 53rd Weather Reconnaissance Squadron—aka the Hurricane Hunters—takes a different approach. They gather their data by flying in and out of the hurricane—and they do it on a regular basis during the hurricane season from June 1st to November 30th. The planes drop between eight and 15 canister shaped probes called dropsondes into the eye and walls of the hurricane. The canister, which deploys a tiny parachute, falls through the hurricane transmitting temperature, pressure, moisture and wind readings directly to the National Hurricane Center in Miami. Each probe sends readings every half second until it falls into the ocean.
Evacuations cost millions and the data collected by these pilots is essential to predicting the hurricane's path and intensity.
Wurman and his team were battered by the hurricane as the eye passed directly over them. The onslaught left them dangling precariously over the bay and within inches of plunging in and being swept away. But it was worth the risk as Wurman and his team have now witnessed the striking forces that explain, at least in part, how houses standing side by side could experience such different outcomes: one shredded and flattened and the other in tact.
As the hurricane season drew to a close, 127 Americans and more than 3,000 in the Caribbean were killed, and the damage was pegged at a total of $42 billion.
National Geographic Explorer's The True Face of Hurricanes delves into the violent science of these giant storms and introduces the brave souls who endure the crashing surf, the howling winds, the torrential rain and the shower of deadly projectiles to keep forecasters and emergency crews on the cutting edge...
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2 Comments
Arent hurricanes as bad as they can be suppose to transfer air and water between the north and south polar regions of the plant earth . in order to balance out the climates. I would like to see cats.4 and 5 hurricanes weaken, so that they wouldnt do some much damages to properties and resevre human livies. We could use the rain from these tropical cyclones.
we need these cat.1 to cat. 2 hurricanes for the rain , and aren,t hurricanes suppose to help balance the air over the surface of the planet_
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