Advertise on Bikeforums.net



User Tag List

Results 1 to 7 of 7
  1. #1
    Senior Member Garfield Cat's Avatar
    Join Date
    Oct 2004
    Location
    Huntington Beach, CA
    My Bikes
    Cervelo Prodigy
    Posts
    4,985
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Wind Chill Calculator

    I ran across this wind chill web site that shows the formulae for both the old method and the new method.

    http://www.onlineconversion.com/windchill.htm

    The formulas used to calculate the wind chill index are:

    Old Wind Chill Index (Pre-November 2001) =
    91.4 - (0.474677 - 0.020425 * V + 0.303107 * sqrt(V)) * (91.4 - T)

    New Wind Chill Index =
    35.74 + 0.6215T - 35.75(V0.16) + 0.4275T(V0.16)

    where:
    V = wind speed (mph)
    T = temperature (F)

  2. #2
    Senior Member hotbike's Avatar
    Join Date
    Dec 2006
    Location
    Long Island, New York
    My Bikes
    a lowrider BMX, a mountain bike, a faired recumbent, and a loaded touring bike
    Posts
    2,542
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I don't know. That's going to require a calculator. And it doesn't take into account the humidity. I know the THI is something else, used on hot days.

    But I believe in using Fairings. So named because they block a strong wind, leaving a fair wind.
    http://www.flickr.com/photos/11629987@N02/sets/72157639939606343/

  3. #3
    Senior Member
    Join Date
    Nov 2008
    Location
    Bay Area, Calif.
    Posts
    4,680
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Neither of those formulas strikes me as reasonable. For example, enter a temperature of 0F and a windspeed of 0 mph. The windchill index at that site comes out as 48F (old formula) or 36F (new formula). Sorry, but if I go outside on a 0 degree day it doesn't feel like it's either 36F or 48F just because the wind isn't blowing.

    The site needs to add some input validity checking. The NWS formula is based on some curve fitting that's only valid for certain ranges of the temperature and wind speeds. Specifically:
    -50F < T < 50F
    3 < WS(mph) < 110
    Last edited by prathmann; 01-15-13 at 12:34 PM.

  4. #4
    7-speed doomsday prepper ThermionicScott's Avatar
    Join Date
    Aug 2011
    Location
    CID
    My Bikes
    1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX
    Posts
    7,675
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    "Windchill" is just a device for sensationalizing the news.
    Quote Originally Posted by chandltp View Post
    There's no such thing as too far.. just lack of time
    RUSA #7498

  5. #5
    Senior Member Garfield Cat's Avatar
    Join Date
    Oct 2004
    Location
    Huntington Beach, CA
    My Bikes
    Cervelo Prodigy
    Posts
    4,985
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    How about just trying to quantify the subjective feeling when the cold air cuts right into your bones? There are days when we go outside on a cold day with no wind and its tolerable but add 15 mph winds, and its a whole different story. In Chicago along the Lakefront, its like that.

  6. #6
    Senior Member digibud's Avatar
    Join Date
    Oct 2009
    Location
    Further North than U
    My Bikes
    Spec Roubaix, three Fisher Montare, two Pugs
    Posts
    1,490
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    My coldest ride this year, with the new wind chill calculator : -48F . But for anyone wearing clothing the wind chill factor is quite meaningless. It might represent how a person would feel if they are naked...but nobody is riding naked. A block of metal at -40F doesn't know if it's windy out or not and if you are wearing a windproof jacket it doesn't make much difference if it's windy or not. Granted you will indeed lose more heat when it's windy but a windchill chart is really kind of meaningless as it pertains to objects that are either ambient temp or protected from the wind like a body in a windproof jacket.
    Once, however, at about -30F I hopped on my snow machine and blasted across a small lake at about 50mph for about a minute. My entire face was flash frozen, superficially and I got a scream as the door was opened to the house where people quickly took me to a sink of warm water. THAT was a case where windchill was very meaningful.

  7. #7
    Senior Member Garfield Cat's Avatar
    Join Date
    Oct 2004
    Location
    Huntington Beach, CA
    My Bikes
    Cervelo Prodigy
    Posts
    4,985
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by digibud View Post
    My coldest ride this year, with the new wind chill calculator : -48F . But for anyone wearing clothing the wind chill factor is quite meaningless. It might represent how a person would feel if they are naked...but nobody is riding naked. A block of metal at -40F doesn't know if it's windy out or not and if you are wearing a windproof jacket it doesn't make much difference if it's windy or not. Granted you will indeed lose more heat when it's windy but a windchill chart is really kind of meaningless as it pertains to objects that are either ambient temp or protected from the wind like a body in a windproof jacket.
    Once, however, at about -30F I hopped on my snow machine and blasted across a small lake at about 50mph for about a minute. My entire face was flash frozen, superficially and I got a scream as the door was opened to the house where people quickly took me to a sink of warm water. THAT was a case where windchill was very meaningful.
    Ok, then that one time your face had no protection but the rest of your body did. Your face was naked.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •