I'm trying to display a conditional windchill using 2m wind speeds ((m/s)>= 0.78)) and air temp ((deg C)>=0.0))
I am using the calculation from the CSI fact sheet using m/s and deg C; 13.127.+0.6215T-13.947V+0.486TV where T is the temp (C) and V is the wind speed (m/s).
here is the RTMC numeric entry. it resolves too cold. The conditional statement works when wind is light or temp is above zero,...was CSI giving me the right cal?
Alias(WS,"Server:grandviewTD.grandview_60min.WS_2Min");Alias(T,"Server:grandviewTD.grandview_60min.Air_T");IIF(WS>=0.78 and T<=0.0,13.127+(0.6215*T)-13.947*WS+0.486*T*WS,$"N/A")
Any help would be much appreciated
Mike
Mike,
This is what I'm doing for a wind chill calculation though this is using degrees fahrenheit and wind speed in mph.
Sub Windchill
WC=35.74+(0.6215*AirTempF)-(35.75*WS_MPH^0.16)+(0.4275*AirTempF*WS_MPH^0.16)
EndSub
Down in the main part of the program I am doing a conditional check to see when I should calculate for Wind chill.
If AirTempF <=40 AND WS_MPH >= 5 Then Call(Windchill)
The calculation is from this website.
http://www.nws.noaa.gov/os/windchill/index.shtml
Hope this helps.
* Last updated by: SEWESA on 11/15/2010 @ 3:50 PM *
Here's what I'm doing to calculate wind chill in RTMC with wind speed in m/s and temperature in °C. I am converting the resulting wind chill temperature to °F before I display it.
ALIAS(T,"Zeus:LoganPeak.Public.AirTemp");ALIAS(V,"Zeus:LoganPeak.Public.WindSpd");IIF(T<=10 AND V>1.34112,(13.127+0.6215*T-13.947*V^0.16+0.486*T*V^0.16)*1.8+32,$"NA")
It's what's being displayed at http://weather.campbellsci.com/lpcc.html
Mostly you missed raising velocities in the equation by the power of 0.16. Also note that windchill is defined for temperatures at or below 50°F (10°C) and wind speeds above 3.0 mph (1.34112 m/s). Your "if" statement is cutting the temperature a little short (0°C) and giving wind speed a little leeway (0.78 m/s). Cutting the temperature short will not generate errors per say, but giving your wind speed leeway into the undefined range will to some degree.
* Last updated by: ChipsNSalsa on 11/18/2010 @ 6:14 PM *