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Displaying THSW data in cumulus
Posted: Mon 27 Oct 2014 7:00 am
by markhadley
Hi
As i'm based in Saigon, the heat index is pretty extreme. The standard display in cumulus (from the Davis Vantage Pro 2 plus) is the Heat Index, however, the THSW is far more valuable to us.
Can you tell me how to get cumulus to display and record this data?
Thanks
Mark
Re: Displaying THSW data in cumulus
Posted: Mon 27 Oct 2014 7:56 am
by steve
Cumulus only makes the value available as a web tag, so it can be displayed on a web page. The web tag is <#THSWindex> - see the wiki for a full list of web tags -
http://wiki.sandaysoft.com/a/Webtags
I seem to recall that there is a problem with the Davis code which supplies one or both of the THW and THSW values, so you may find that it doesn't actually work anyway.
Re: Displaying THSW data in cumulus
Posted: Mon 27 Oct 2014 7:21 pm
by duke
steve wrote:
I seem to recall that there is a problem with the Davis code which supplies one or both of the THW and THSW values, so you may find that it doesn't actually work anyway.
Just the THSW refuses to function correctly,
see here.
Re: Displaying THSW data in cumulus
Posted: Mon 27 Oct 2014 9:16 pm
by GraemeT
Mark,
I think there's enough information here:
http://www.bom.gov.au/info/thermal_stress/index.shtml to be able to calculate a THSW index in PHP or Javascript. It's quite similar to the method used to calculate "apparent temp".
edit:
This PHP function might work (I haven't tested it as I can't measure solar radiation)
Code: Select all
function thsw_index($temp,$hum,$wspeed,$SolarRad) {
$e=$hum/100*6.105*exp(17.27*$temp/(237.7+$temp));
$ws=($wspeed*1000)/3600;
$thsw_index=round(($temp+0.348*$e-0.70*$ws+0.70*$SolaRad/($ws*10)-4.25),1);
return $thsw_index;
} // end of thsw()