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 About RF Cafe Copyright: 1996 - 2024Webmaster:    Kirt Blattenberger,     BSEE - KB3UON RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived... All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged. My Hobby Website: AirplanesAndRockets.com

# Windchill Chart - Wind Speed vs. Air Temperature

 Frostbite Times 30 minutes 10 minutes 5 minutes
I am more of a cold weather person than a hot weather person. However, cold does tend to slow down the movement of my fingers, so working outside without gloves is very challenging.  This information is derived from NOAA. Here is a heat index chart.

In 2001, NWS implemented an updated Windchill Temperature (WCT) index (see table below).

NOAA provides the following equation for calculating wind chill:

Wind Chill (°F) = 35.74 + 0.6215T -
35.75(V0.16) + 0.4275(V0.16),
where T = Air Temperature (°F),
V = Wind Speed (mph)

 Wind(mph) Temperature (°F) 40 35 30 25 20 15 10 5 0 -5 -10 -15 -20 -25 -30 -35 40 5 36 31 25 19 13 7 1 -5 -11 -16 -22 -28 -34 -40 -46 -52 -57 10 34 27 21 15 9 3 -4 -10 -16 -22 -28 -35 -41 -47 -53 -59 -66 15 32 25 19 13 6 0 -7 -13 -19 -26 -32 -39 -45 -51 -58 -64 -71 20 30 24 17 11 4 -2 -9 -15 -22 -29 -35 -42 -48 -55 -61 -68 -74 25 29 23 16 9 3 -4 -11 -17 -24 -31 -37 -44 -51 -58 -64 -71 -78 30 28 22 15 8 1 -5 -12 -19 -26 -33 -39 -46 -53 -60 -67 -73 -80 35 28 21 14 7 0 -7 -14 -21 -27 -34 -41 -48 -55 -62 -69 -76 -82 40 27 20 13 6 -1 -8 -15 -22 -29 -36 -43 -50 -57 -64 -71 -78 -84 45 26 19 12 5 -2 -9 -16 -23 -30 -37 -44 -51 -58 -65 -72 -79 -86 50 26 19 12 4 -3 -10 -17 -24 -31 -38 -45 -52 -60 -67 -73 -81 -88 55 25 18 11 4 -3 -11 -18 -25 -32 -39 -46 -54 -61 -68 -75 -82 -89 60 25 17 10 3 -4 -11 -19 -26 -33 -40 -48 -55 -62 -69 -76 -84 -91

Note: Even NOAA uses both "windchill" and "wind chill" on their website, so
the two forms appear to be interchangeable.

Clinical trials were conducted at the Defence and Civil Institute of Environmental Medicine in Toronto, Canada, and the trial results were used to improve the accuracy of the new formula and determine frostbite threshold values. Standardization of the WCT Index among the meteorological community provides an accurate and consistent measure to ensure public safety. The new wind chill formula is now being used in Canada and the United States.

Specifically, the new WCT index:
• Calculates wind speed at an average height of five feet (typical height of an adult human face) based on readings from the national standard height of 33 feet (typical height of an anemometer)
• Is based on a human face model
• Incorporates modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days)
• Lowers the calm wind threshold to 3 mph
• Uses a consistent standard for skin tissue resistance
• Assumes no impact from the sun (i.e., clear night sky)
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