Wind Chill 1.0  Copyright (c) 1996 Tan Kok Mun
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1. WHAT IS THE WIND CHILL INDEX

   Several formulas exist for calculating wind chill. The formula used in
   this program is based on a formula provided by the Midwestern Climate 
   Center. This is a cooperative program of the U.S. National Weather 
   Service and the Illinois State Water Survey in Champaign, Illinois. 
   
   The formula used to calculate the wind chill index is:

      Wind Chill=91.4-(0.474677-0.020425*V+0.303107*sqrt(V))*(91.4-T)

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

   Everyone knows that your outdoor comfort depends on several factors, 
   only one of them being temperature. Factors such as whether it's sunny 
   or cloudy, windy or calm, damp or dry, can also play an important role.
   One popular approach in measuring the level of discomfort (and potential 
   danger from frostbite) is the wind chill index. The wind chill index 
   takes into account both the temperature and wind speed. The wind chill 
   index is a useful rule-of-thumb for making decisions about outdoor 
   activities.

   The important thing to remember is that the wind chill index is a measure
   of the rate of heat loss, and is not a temperature. For example, the wind
   chill index tells you how quickly heat is lost to the wind, not how cold
   your fingers, a car radiator, or a glass of water will get. Further, a
   glass of water will not freeze if the air temperature is above freezing 
   and the wind chill is below freezing. Or, if your car's antifreeze is 
   good down to -30F, wind chills below -30F will not harm your car (only if 
   the air temperature drops below -30F are you in trouble). For humans, 
   there is no specific rule for determining when wind chills become 
   dangerous. However, wind chill values below -20F appear to significantly 
   increase your risk of frostbite."

   It is also useful for anyone moving in cold temperature, for example bike
   riders and sailors. For this scenerio, use your vehicle speed as the Wind
   Speed.


2. USE OF THE PROGRAM

   When you run the program, you will see the following screen :

      Temperatur.________  Note:Temperature spelling is truncated due
      Wind speed ________       to display space limitation.

     Chill Index ________

    <OK> <CANCEL> <A> <B>

   To calculate the Chill Index, provide both the temperature and wind 
   speed information.

   For the temperature, it can be in either Ferenheit or Celsius. To 
   indicate which temperature unit to use, suffix your value with a "c" or
   "C" for Celsius and no suffix or other suffix (other than "c" and "C") 
   for Ferenheit.

   For the wind speed, it can be in either MPH, KM/H or KNOTS. To indicate
   which unit to use, no suffix or other suffix (other than "k", "K", "n"
   and "N") for MPH, suffix it with "k" or "K" for KM/H and "n" or "N" 
   for KNOTS.
   
   Wind speeds above 40 MPH or equivalent have little additional chilling 
   effect, and any speed you enter above 40 MPH will be calculated as 40 MPH.

   Wind speeds below 4 MPH or equivalent has no chilling effect, any speed
   you enter below 4 MPH will return the a chilling index equal to the
   temperature.
   
   Press <OK> to calculate the Wind Chill Index. The Chill Index will be
   in the same unit measurement as the temperature.

   There is a built in warning message that warns you when the Wind Chill
   Index is below -20F. This level is the potential Frost Bite level.

   Example 1.
   To calculate the Wind Chill Index at 10 Celcius and a wind speed of 
   5 KM/H.
      
         Temperatur. 10c_____  <<<--- Suffix with "c", to indicate celsius
         Wind speed  5k______  <<<--- Suffix with "k", to indicate KM/H

        Chill Index  ________
     
        <OK> <CANCEL> <A> <B>

   And you will see the Wind Chill Index is 6.086814C.

   Example 2.
   To calculate the Wind Chill Index when you are travelling at 40MPH and
   the temperature is 19F.

         Temperatur. 19______   <<<--- No suffix, ie default to Ferenheit
         Wind speed  40______   <<<--- No suffix, ie default to MPH

       Chill Index F ________
     
        <OK> <CANCEL> <A> <B>

   And you will see the Wind Chill Index is -22.607844F, and a warning
   for potential Frost Bite.


3. HISTORY
   Version 1.0 - First Release.
