Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!zehntel!hplabs!sri-unix!parallel!den From: den@parallel.UUCP (Dennis Briscoe) Newsgroups: net.sci Subject: Wind Chill Factor? Message-ID: <244@parallel.UUCP> Date: Thu, 2-Aug-84 15:43:58 EDT Article-I.D.: parallel.244 Posted: Thu Aug 2 15:43:58 1984 Date-Received: Sun, 5-Aug-84 05:27:29 EDT Lines: 35 Can anyone tell me how wind chill factors are calculated? I often hear television and radio announcers talk about how cold it is at a football game, etc. "The temperature is 12 degrees fahrenheit with the wind chill factor making it -20 degrees." With just a little thought one realizes that it isn't likely that air at 12 degrees could cool an object down to -20 degrees. It won't likely cause a pond to freeze, for instance. There could be some cooling due to faster evaporation, but is the wind chill factor dependent on the humidity of the air and the surface moisture of the object in question? When I discussed this question with another person at work some time ago, he said that since the body warms the air around it, thermal layers of air form. These layers are stripped off by the wind. This makes a lot of sense to me, but it still means that the wind chill factor is dependent on the amount of heat transferred from the body (or from any object whose tem- perature is higher than ambient). The internal temperature and the type of insulation on a person or other object would make a big difference. In the "12 degrees / -20 degrees" example, if a block of ice were on the field, it would melt faster than it would with no wind at 12 degrees, and of course at -20 degrees it wouldn't melt at all. Perhaps wind chill factor is only supposed to be a rough guideline for adjusting calculations for probable survival time in the wilderness. Many of the questions still apply, and as I have mentioned, it is often used in other contexts. So, my questions are, "How is wind chill factor calculated?", "Is it scien- tifically valid?", "Does it apply only to humans?", and "What assumptions are made about clothing, etc.?" Einstein didn't know beans, (but that's another story) Dennis Briscoe - - Parallel Computers