Windchill Calculation

[David K. <da...@kj...>]

Just a note of praise for the PHP Weather....great
program. Thanks to the entire team for a very useful
program.

Below is a modification I made to the .inc program to
calulate windchill in both F and C. I placed this code
right after the relative humidity calc in the process
metar function. I also modified the locale-en.inc to
print a "The windchill is..." statement in the full
pretty print. Note the condition that temperature be
below 40f and wind above 3 mph for the calculation to
be valid. These conditions are a combination of the F
and C version requirements. Also, these equation are
the "new" windchill formula released about Nov 2001.

I hope you guys consider this little addition.

 /*
   *  Compute windchill if temp < 40f and windspeed >
3 mph
   */
  if ($decoded_metar['temp_f'] <= '40' &&
$decoded_metar['wind_miles_per_hour'] > '3'){
     $decoded_metar['windchill_f'] =
number_format(35.74 + 0.6215*$decoded_metar['temp_f']
-
35.75*pow($decoded_metar['wind_miles_per_hour'],0.16)
+
0.4275*$decoded_metar['temp_f']*pow($decoded_metar['wind_miles_per_hour'],0.16));
     $decoded_metar['windchill_c'] =
number_format(13.112 + 0.6215*$decoded_metar['temp_c']
-
13.37*pow(($decoded_metar['wind_miles_per_hour']/1.609),0.16)
+
0.3965*$decoded_metar['temp_c']*pow(($decoded_metar['wind_miles_per_hour']/1.609),0.16));
     
    }