Temperature in my snakes cage

So I have a 2 month old corn snake in a 30" x 12" x 12" or a 30 gallon tank with a UTH, a piece of driftwood (bought from the pet store), a water bowl(on cool side), and a log hide(also purchased from pet store). So I want to know what counts as the actual temperature that I should go by, the ground temp or the air temp? By the way the air(ambient) temp is around 65 to 75 on the warm side and around the same on the cooler side at all times. Also the ground temp is 78 to 85 on the warm side and around 72 to 75 on the cooler side. Is that allrite?

You should definitely measure by the ground temp since that is where your snake is. They need the belly heat to digest their food. I keep the probes from my thermometers buried about 1/3 of the way down in the substrate. That way you can avoid burning your snake by trying to heat the ambient air with a UTH.

Your temps are good like that. Try to keep the high temp side closer to the mid-eighties than high seventies.
You should measure the max temp on top of the UTH, under the substrate, just to make sure its not too high. I keep my temp probe there just in case. I know when it is about 88 on the UTH, it is then about 84ish in her warm hide.

Good advice above. Don't worry about the ambient air temperature - I assume that's the general temperature of the air in the tank. Your snake stays at floor level, so that's where you need to measure and control the temps.