Davis Instruments Weather Club
October 2001
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Here's a quick preview of this month's contents:
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National Weather Service Announces New Wind Chill Formula . . . Vantage Pro Named Official Weather Station of the 2001 Kodak Albuquerque International Balloon Fiesta . . . Back to School: New Teacher's Guide in the Works . . . Update on NOAA Citizen Weather Observer Program . . . Enjoy!
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National Weather Service Announces
New Wind Chill Formula
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This winter, as cold air and icy winds return to the Northern Hemisphere, the National Weather Service will be using a new formula to calculate wind chill--one they say will more accurately reflect how cold it really feels.
The original formula was developed in the 1940's by Antarctic explorers Paul Siple and Charles Passel. Studying plastic cylinders filled with water, they found that the amount of time it took the water to freeze varied depending on the original temperature of the water, the ambient air temperature, and the average wind speed.
But a cylinder of water is not the same as a human body. Unlike the water in the cylinder, the human body continues to generate its own heat. Human skin also freezes at a different rate than water does, and different parts of the body are more susceptible to freezing than others. In addition, the old system used wind speed measured at 33 feet above ground, where the wind typically blows much faster than it does at "face level," defined as 5 feet above ground.
Recognizing these differences, a joint U.S.-Canadian task force conducted a study using actual human volunteers. With temperature sensors attached to their faces, these hardy souls withstood numerous wind tunnel tests under various combinations of wind speed and temperature. The result: a new wind chill formula that, according to the National Weather Service, will provide much more accurate information.
The basic concept behind both formulas is the same: moving air carries heat away from the body more effectively than air that is not moving. When winds are light (10 mph or less), the new numbers aren't significantly different from the old ones. But they're substantially less extreme as wind speeds increase. For example, under the old system, a temperature of 20 degrees F and a wind speed of 15 mph would have resulted in a wind chill of 5 degrees below zero. Under the new system, the wind chill is a relatively balmy 6 degrees above zero.
The gap becomes wider as conditions worsen. So the bitter cold and biting wind that would have resulted in a wind chill of 70 below last winter will work out to just 44 below this year. But that's still pretty cold, in our estimation!
Both the Canadian and U.S. weather services will begin using the new formula this fall, as the changes are programmed into their computers and colder temperatures return to the continent. Here at Davis, our crack team of engineers were quick to react to the announcement, and all Vantage Pro stations currently being produced now feature the new formula.
You can check out the new wind chill charts at the National Weather Service's site, http://www.srh.noaa.gov/ftproot/ssd/html/windchil.htm, where you'll also find an on-line wind chill calculator.
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Vantage Pro Named Official Weather Station of the
2001 Kodak Albuquerque International Balloon Fiesta
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We're proud to announce that our new Vantage Pro™ has been named the official weather station of the 2001 Kodak Albuquerque International Balloon Fiesta. An annual spectacle of color and adventure, it's the most photographed event in the world. Now celebrating its thirtieth anniversary, this year's Fiesta will take place over nine days, from October 6 through 14.
At the Albuquerque Fiesta, the balloon crews will assemble in the cold, pre-dawn air each morning of the event to begin the task of inflating the balloons. Come sunrise, the balloons will be released from their moorings to begin the spectacular mass ascension.
Why so early in the morning? The air is typically the calmest in the morning and evening hours, when the sun is low in the sky. High winds can be dangerous--filling up the balloon is tough to do when winds are strong, and strong winds can also cause the balloon to drag the basket when landing.
But it's not just the overall weather patterns that matter. According to Fiesta meteorologist Randy LeFevre, Albuquerque is a place of micro-meteorology. The weather is very terrain-driven, and there is wind flow off small hills, flat surfaces, and even the parking lot filled with cars. And this is where the Davis weather station comes in.
The Vantage Pro Integrated Sensor Suite will be located on the launch field, and wireless data packets will be sent to the console back inside the Pilot Command Center every 2.5 seconds. Pilots will be able to obtain real-time weather information just minutes before take-off. According to Randy, individual pilots make the decision to fly based on their own experience. Inexperienced pilots may be more intimidated by stronger winds than are seasoned vets, but all make decisions in real time.
Like all commercial and private aircraft, hot air balloons were grounded in the aftermath of the World Trade Center disaster. We hope that return to the skies will remind us all that the American spirit lives on.
To find out more about the Balloon Fiesta, or to sign up for e-mail updates about the event, visit http://www.balloonfiesta.com. For more information about hot air ballooning in general, check out http://www.launch.net. Another good site is the NOVA site, a part of PBS online, where you can delve into the history of science and ballooning, follow the attempts of earlier balloonists to make the round-the-world flight, and more. (There, we learned about the world's first hot air balloon. Launched in 1783, it carried a duck, a sheep, and a rooster!) You'll find the NOVA site at http://www.pbs.org/wgbh/nova/balloon.
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Back to School: New Teacher's Guide in the Works
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September marks the beginning of the school year here in North America. As the days grow shorter and the air more crisp, we watch our kids go off to school and remember our own school days.
A growing number of schools are incorporating Davis weather stations into their science curriculum, and we're pleased to report that HOW THE WEATHERWORKS, a nationwide educational weather services company, is collaborating with Davis Instruments to develop a comprehensive multi-disciplinary weather curriculum guide for the start of the 2002-2003 school year.
The guide will be centered around individual Davis system data, but will be linked to other single-station sites via Internet applications. Although designed for use by teachers and students in grades 2-12 (with separate sections for elementary, middle and high school levels), the guide should be valuable for any weather enthusiast who wishes to learn more about meteorology.
Mike Mogil, a national weather educator and Certified Consulting Meteorologist, and Barbara Levine, an elementary math-science specialist, are heading up the development team. They'd welcome input from teachers who use Davis weather stations in their classrooms. In addition to providing different geographical perspectives (the weather certainly does vary a lot in the US depending on where you live!), teachers can share experiences about what works (and what doesn't), provide input on how the system meets state and national educational standards in math and science, and suggest other possible venues for developing appropriate activities.
If you would like to contribute to this effort, please contact Mike and Barbara directly at weatherguide@weatherworks.com.
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Update on NOAA Citizen Weather Observer Program
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Last month, we told you how you could participate in the NOAA Citizen Weather Observer Program. According to Joe Schmidt, Internet Coordinator for the program, “After the Davis newsletter hit the street, W4EHW was deluged with observer inquiries.”
Joe also told us that it was a volunteer observer, Mark Sudduth of the Hurricane Intercept Research Team, who provided the Center with the maximum reading during last August’s Tropical Storm Barry. Mark reported a sustained wind speed of 66 mph, with gusts to 84 mph, along Highway 98 near Panama City, Florida.
Many thanks to all of you have signed up for this worthwhile program. And here's some good new for Vantage Pro owners: the W4EHW team recently updated their software (available for free on their website) so that it now accepts our new Vantage Pro weather stations in addition to our earlier models.
If you haven't signed up yet, but would like to, it's not too late. For details, see our story in last month’s e-newsletter, http://www.davisnet.com/news/e_news_archive/0108.asp.
