I am looking for equations valid at temps up to 500 degrees F, that allows one to calculate the relative humidity for air based on wet bulb and dry bulb temps. Everything that I can find is only accurate at lower temps. For that matter I can't even find a psychrometric chart that goes that high. Am I missing something here? Any ideas? I need to calculate the wet bulb temp based on the rh, and Tdry, over the same range as well, but I can work around this if needed.