There's a neat article
over here about how Nissan has set up a sonic cannon to protect its cars from hail storms.
For those of you too lazy to click on a link, read the fine print below.
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Jackson 02/03/04
Nissan Uses Device to Stop Hail
By Bert Case
bert@wlbt.net
Nissan demonstrated its new device designed to protect its parking lot from a hailstorm for WLBT News on Tuesday. It is a cannon that sends sonic waves up to 50,000 feet in the air to keep hailstones from forming.
There are more than 400 such machines in operation in the world, and this is the ninth one installed in the United States. They are made in Canada and are used primarily to protect crops. It works by using its own radar to detect the conditions that are favorable for hail to form.
It automatically activates when its own weather radar system detects conditions favorable for the formation of hail. It fires every 5.5 seconds, making a sound we know can be heard at least five miles away from the Nissan plant near Canton. It then starts sending sound waves into the cloud every five-and-a-half seconds.
The sound at ground zero is about 120 decibels, or about the same as a tornado warning siren. Workers are installing fences around two of the machines in the 140-acre parking lot at Nissan and filling the fences with hay in an effort to reduce the sound level.
Eric Rademacher is an environmental engineer with Nissan who is an expert on the Hail Suppression System.
"Hailstones are formed and begin with a piece of dust in the clouds," he explains. "There is a lot of activity going on, and what we do is to de-ionize that activity in the clouds and keep those dust particles from collecting moisture out of the clouds in turn reacting and forming what we know as a hailstone."
If you ever hear this system activate in Madison County near Nissan, it's time to get yourself and your vehicle protected from hailstones.
Nissan hopes it will save millions of dollars worth of vehicles from hail damage. They won't say what it cost, but admit they won't really know if it works until there is a hail storm over the plant. The sound is produced by igniting the same material used for welding.
This is the first such machine used by an auto-manufacturer. The man who installed it bought a Nissan Pathfinder Armada, which is made at the plant.
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