QB64 Phoenix Edition
Anyone know how frostbite thresholds are calculated? - Printable Version

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RE: Anyone know how frostbite thresholds are calculated? - Kernelpanic - 02-04-2023

(02-04-2023, 10:17 PM)bplus Wrote:
Code: (Select All)
Input "Farenheight temp"; T
Input "Wind MPH"; V
Print Wind_Chill(T, V)

Function Wind_Chill (T, V)
    Wind_Chill = 35.74 + 0.6215 * T - 35.75 * (V ^ 0.16) + 0.4275 * T * (V ^ 0.16)
End Function



Please don't grade me on spelling ;-))

Quote:The question is: how do you put the brackets? 

Yes, there is a problem with the calculations! I noticed this today on this page: Wind Chill Calculator

For Celsius you have to select "k/h", for Fahrenheit "mph", otherwise the result will not be correct. But why is the result different again in your example?

[Image: Wind-Chill-Problem2023-02-04-232148.jpg]

RE: Anyone know how frostbite thresholds are calculated? - SMcNeill - 02-04-2023

If you want a Celius and KpH windchill chart, take a look at this one:

Code: (Select All)
SCREEN _NEWIMAGE(800, 600, 32)
$COLOR:32
PRINT "  ";
count = 1
FOR temp = 40 TO -45 STEP -5
    LOCATE , 4 * count
    PRINT temp;
    count = count + 1
NEXT
PRINT


FOR windspeed = 5 TO 60 STEP 5
    COLOR White, Black
    PRINT windspeed;
    COLOR Black, SkyBlue
    count = 1
    FOR temp = 40 TO -45 STEP -5
        wc& = WindChill(temp, windspeed)
        LOCATE , 4 * count
        count = count + 1
        SELECT CASE wc&
            CASE IS > -18: COLOR Black, LightBlue
            CASE IS > -32: COLOR White, SkyBlue
            CASE IS > -48: COLOR White, Blue
            CASE ELSE: COLOR White, Purple
        END SELECT

        PRINT wc&; " ";
    NEXT
    PRINT
NEXT

COLOR White, Black

PRINT: PRINT
PRINT "Celius and Windspeed in KpH"
PRINT "  ";
count = 1
FOR temp = 40 TO -45 STEP -5
    LOCATE , 4 * count
    PRINT F2C(temp);
    count = count + 1
NEXT
PRINT


FOR windspeed = 5 TO 60 STEP 5
    COLOR White, Black
    PRINT M2K(windspeed);
    COLOR Black, SkyBlue
    count = 1
    FOR temp = 40 TO -45 STEP -5
        wc& = F2C(WindChill(temp, windspeed))
        LOCATE , 4 * count
        count = count + 1
        SELECT CASE wc&
            CASE IS > -18: COLOR Black, LightBlue
            CASE IS > -32: COLOR White, SkyBlue
            CASE IS > -48: COLOR White, Blue
            CASE ELSE: COLOR White, Purple
        END SELECT
        PRINT wc&; " ";
    NEXT
    PRINT
NEXT


FUNCTION WindChill& (temp AS _FLOAT, windspeed AS _FLOAT)
    WindChill = 35.74 + 0.6215 * temp - 35.75 * windspeed ^ 0.16 + 0.427 * temp * windspeed ^ 0.16
END FUNCTION

FUNCTION F2C& (temp)
    F2C = (temp - 32) * 5 / 9
END FUNCTION

FUNCTION M2K (mile)
    M2K = 1.609344 * mile
END FUNCTION


First chart is "Americanized" while the second is "Europeanized".

RE: Anyone know how frostbite thresholds are calculated? - Kernelpanic - 02-05-2023

Mischief deleted!  Confused

RE: Anyone know how frostbite thresholds are calculated? - James D Jarvis - 02-06-2023

"Only issue is my color values don't match.  Anyone know why -62 windchills are light blue at the top of the chart, but then are purple at the bottom?  If the implied temperature is -52 in both cases, shouldn't frostbite occur at the same time?  Isn't that basically what windchill is for -- to give an equal representation of what the temperature would feel like it the wind wasn't blowing?"

The wind makes it worse.  The charts are really just a rough estimate. 
I can split wood in a t-shirt , hat, and gloves down to about 6F if there is no breeze to speak of. The wind will penetrate your clothing, the cold itself takes a while to do that if you are fit and active and your clothing is halfway decent.

I've gone winter camping where we snowshoed in and slept in an open-faced shelter when we were getting wind chills in the -30 to -40 range. Next morning when it was 11F  and not breezy much at all outside we were almost sweating while snowshoeing out.

This weekend is the first time in years I've had 5 layers on my torso to not freeze when outside (still only needed 2 pairs of socks because there was no way on earth my feet were getting wet when it was that cold).