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| Sunday, 2 October 2005 |
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Junior Observer |  |
| News Business Features Editorial
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Chasing hurricanes and tornadoes
Hurricane Katrina killed hundreds of innocent victims in New Orleans, America and displaced thousands more. Now there is Hurricane Rita, causing further damage. Most people - especially those living in the American Midwest - know how to boost their chances of survival during such incidents. First, get into a basement or a storm cellar. If that's not possible, hide in an interior, windowless room, preferably under a mattress or blankets. Never stay in a car or a mobile home - lying in a ditch, though definitely uncomfortable in the middle of a severe storm, is a lot safer. Some people ignore this advice and become tornado chasers, but even chasers generally stay about a mile away from a tornado - close enough to see, but relatively out of danger. Anyone wanting a closer look, or to actually get a glimpse of the interior of a tornado, would need a heavy, armoured vehicle that could withstand intense winds, debris and hail. That's exactly what IMAX cinematographer (film-maker) Sean Casey has built with his Tornado Intercept Vehicle (TIV). The TIV is big, heavy and armour plated. With it, Casey hopes to record a direct hit with a tornado and survive. The TIV is essentially a large, mobile, armoured tripod for an IMAX camera. Its purpose is to allow film-makers to record footage from very close to - or even inside of - a tornado. The current Tornado Intercept Vehicle is really a prototype (trial model), and it has undergone a number of modifications since its first season in the field. A second vehicle, the TIV-2, will include additional features like steel panels that drop down when the vehicle is in the path of a tornado. These panels will keep air from getting under the vehicle and reduce the likelihood of becoming airborne. The TIV was originally a Ford F450 pick-up truck. Its transformation into the TIV took three months of seven-day-a-week work. After stripping it down to its engine and chassis, Casey created a new frame and body out of steel. Tyres need to be accessible, yet protected from debris, so a hinged 1/8 inch steel flap covers each wheel well. Each of the four doors features a double layer of 1/8" steel plate. When closed, the doors lock into place with heavy steel bolts. The TIV's side windows are 1/2" Lexan resin, a very strong plastic. For better visibility, its windshield is a scratch-resistant tempered glass and Lexan laminate. Since the TIV's purpose is to provide a safe spot for filming, it has a special military-style turret to house the IMAX camera. The turret spins 360 degrees on 3" steel bearings, allowing the crew to shoot footage in any direction. The TIV also has two hatches for smaller format cameras. Including its skeleton and frame, the TIV weighs almost 14,000 pounds. In spite of all this weight, it can reach up to 90 mph. A lot of work went into building the TIV, and a significant number of repairs have gone into keeping it running. So why not just use a tank? A primary reason is that tanks generally travel at much slower speeds than the TIV. Tornadoes can develop and dissipate(fade away) within a few minutes, so speed is important to tornado chasers. Since the TIV is built around a pick-up truck's engine and steering, no special training is required to drive it. Since it can survive very high winds and hail, the TIV provides a good opportunity to collect tornado data. Inside the TIV are a variety of meteorological instruments, including a blade anemometer, which measures wind speed and force in one dimension, a sonic anemometer, which also measures wind speed and force, but in three dimensions, two global positioning system (GPS) units and tools for measuring temperature, pressure and humidity. Another weather research tool, the Doppler on Wheels (DOW), also uses the same instruments in addition to a mobile Doppler radar. The DOW, however, must stay between two and eight miles away from a tornado. Since the TIV houses the same instruments as the DOW, scientists can combine their data to create a more complete picture of the life of a tornado. Scientists are eager to know more about tornadoes. What exactly causes them? What factors determine their strength? Why do they behave the way they do? Two of the major projects underway to gather and analyse more data about tornadoes are Radar Observations of Tornadoes and Thunderstorms (ROTATE) and Verification of the Origin of Rotation in Tornadoes Experiment (VORTEX) - 2. What happens when the TIV chases a tornado? That depends on whether Casey and his team are working with other chasers or independently. The first step is always research. All storm chasers must determine where tornadoes are likely to form and which approach to the storm will give them the best view while keeping them out of the most dangerous parts of the storm. The TIV crew takes precautions to help ensure their safety. In addition to using data from their instruments and those of other chasers to gauge the strength of the storm, they wear helmets and goggles during their intercept attempts. A worst case scenario for the chase crew would include a rapidly strengthening tornado, wind speeds much higher than those recorded on the TIV instruments or estimates based on other chasers' data, an impact from the most powerful part of the tornado's funnel and a broadside impact, where the surface area of the TIV is greatest. With these factors present, a tornado could theoretically lift or move the TIV, or pull it apart. |
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