All Apps and Add-ons

How to determine wet bulb temperature from dry temp, humidity, and pressure.

wweiland
Contributor

Well, I spent the better part of a day figuring this out and figured I would share.

This is for all of those poor HVAC souls who need wet bulb temp. I would suggest installing TA-wunderground and pull the data into a index. Then you can run the following query to get dry and wet bulb temps. I have compared this against NOAA's online calculator and it's pretty close. Spot on when it's 40 or above and a few tenths of a degree off when freezing.

index=weather | table _time, temp_f, temp_c, pressure_mb, relative_humidity | eval rh=substr(relative_humidity,1,len(relative_humidity)-1) | eval tdc=round(temp_c-(14.55+0.114*temp_c)*(1-(0.01*rh))-pow(((2.5+0.007*temp_c)*(1-(0.01*rh))),3)-(15.9+0.117*temp_c)*pow((1-(0.01*rh)),14),10) | eval e=round(6.11*pow(10,(7.5*tdc/(237.7+tdc))),10) | eval wbc=round((((0.00066*pressure_mb)*temp_c)+((4098*e)/pow((tdc+237.7),2)*tdc))/((0.00066*pressure_mb)+(4098*e)/pow((tdc+237.7),2)),2) | eval wbf=wbc*1.8000+32 | timechart span=15m last(temp_f) as "dry bulb temperature", last(wbf) as "wet bulb temperature"
0 Karma
1 Solution

wweiland
Contributor

Any issues, speak up.

View solution in original post

0 Karma

wweiland
Contributor

Any issues, speak up.

0 Karma
Get Updates on the Splunk Community!

SOC4Kafka - New Kafka Connector Powered by OpenTelemetry

The new SOC4Kafka connector, built on OpenTelemetry, enables the collection of Kafka messages and forwards ...

Your Voice Matters! Help Us Shape the New Splunk Lantern Experience

Splunk Lantern is a Splunk customer success center that provides advice from Splunk experts on valuable data ...

Building Momentum: Splunk Developer Program at .conf25

At Splunk, developers are at the heart of innovation. That’s why this year at .conf25, we officially launched ...