Cumulus Support

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// ------ Calculate delta T --------------------------------------------------------
// needs tempC, dewpointC, pressureABS, (baro_offset is YOUR difference to ASL)

element = document.getElementById("delta_T");

if(element){
			
	temp = parseFloat(temp);
	dewpoint = parseFloat(dewpoint);
	baro = parseFloat(baro);
			
	if(pressunit == "inHg") {
		MBpressure = parseFloat(convertinHGtomb(baro)) - parseFloat(convertinHGtomb(baro_offset));
	} else {
		MBpressure = baro - baro_offset;
	}
			
				
tempunit = tempunit.substr(5);
	if (tempunit == "F") {
		Ctemp = parseFloat(convertFtoC(temp));
		Cdewpoint = parseFloat(convertFtoC(dewpoint));
	} else {
		Ctemp = temp;
		Cdewpoint = dewpoint;
	}
			
	E1 = parseFloat(esubx(Cdewpoint));
			
	Twguess = Cdewpoint;
	incr = 10;
	previoussign = 1;
	Edifference = 1;
			
	wetbulb = calcwetbulb(Edifference,Twguess,Ctemp,MBpressure,E1,previoussign,incr);
// NB - you've got a wet bulb (C) temp ;-)
	delT = roundOff(temp - wetbulb)
	element.innerHTML = delT;
							
}	// END calculate delta T



function esubx(temp) {
	var Ex;
	Ex = 6.112 * Math.exp((17.67 * temp) / (temp + 243.5));
	return Ex;
}    // END

			
function calcwetbulb(Edifference,Twguess,Ctemp,MBpressure,E,previoussign,incr) {
	outerloop:
	while (Math.abs(Edifference) > 0.05) {
		Ewguess = 6.112 * Math.exp((17.67 * Twguess) / (Twguess + 243.5));
		Eguess = Ewguess - MBpressure * (Ctemp - Twguess) * 0.00066 * (1 + (0.00115 * Twguess));
		Edifference = E - Eguess;
					
		if (Edifference == 0) {
			break outerloop;
		} else {
			if (Edifference < 0) {
				cursign = -1;
				if (cursign != previoussign) {
					previoussign = cursign;
					incr = incr/10;
				} else {
					incr = incr;
				}
			} else {
				cursign = 1;
				if (cursign != previoussign) {
					previoussign = cursign;
					incr = incr/10;
				} else {
					incr = incr;
				}
			}
		}
		if (Math.abs(Edifference) <= 0.05) {
			break outerloop;
		} else {
			 Twguess = Twguess + incr * previoussign;
		} 
	}
	wetbulb = Twguess;
	return wetbulb;
}	// END
			
			
							
function RH(E,Es) {
   var RH;
   RH = 100 * E/Es;
   return RH;
}


function roundOff(value) {
	value = Math.round(100*value)/100;
	return value;
}    // END