Wet Bulb Depression


Has anyone used the relative humidity chart in the latest IRPG? Did you notice instead of wet bulb readings on the top row there is a wet bulb depression number? Are newer belt weather kits providing these same RH charts? Does anyone know why it was changed? Are there additional charts available somewhere for more than the only two elevation ranges provided in the IRPG? Why wasn’t this included in the list of updates for the new guide? This may be an old topic but I haven’t seen it. I’m still teaching our new hires how to sling weather and field calculate fine dead fuel moisture using the IRPG in case of digital failure. Hopefully some information on this topic is generated here.
Thank You


I never use the tables in the IRPG due to the elevation range issue (the last one was that way as well). I always use the tables that come with the kit (or print replacement tables if they are missing or damaged). Wet bulb depression should be easy enough to teach, then they can figure it out no matter what table they get.



Thanks for the tips. I’m a little humbled that I’m just now picking up on that change if has existed for two IRPG prints. I do, however, also usually use the charts in the belt weather kit. Or more frequently a kestril.

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I use the charts from the Wildland Fire Module Field Guide

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I love that guide. I highly recommend it.


Thanks you!