Surface Temperature of Field Turf

Does he have the slightest bit of rationale for what he considers "too hot?" I see a lot of problems here.

1) Those IR guns really depend on a universal assumption for the emissivity of the surface being measured. That is to say, everything radiates heat to some degree, as a function of its absolute temperature to the 4th power and a factor determined by the material. If the turf gives out more energy at a given temperature than the average estimated by the IR gun company, you'll get an artificially high number.

2) Assuming the actual temperature of the turf IS ~140 F, that doesn't in any way mean that it's dangerous. That grill analogy is pretty good, and it's even more accurate over the turf field. Obviously, the air temperature is nowhere near 140, so the turf is taking in more heat (from the sun) than its giving out (into the air above it). The air above the turf is way way cooler. Furthermore, the air over the field is not sitting still, it gets dispersed by any breeze, and actually creates its own breeze when the bottom layer of air rises (that old hot air rising thing) and gets replaced by cooler air from beside the field.

3) He may be worried about burns from contact with the field but that isn't a big issue because a) 140 F isn't THAT hot, b) Although convection (heat transfer between solid and fluid) and conduction (heat transfer between two solids) aren't exactly the same, there is a relationship, and as discussed above, turf isn't very good at transferring heat. A metal barbecue grill is designed to cook your food and transfer heat, turf is not.

4) I have the impression from your post he bought this thing at Wal-Mart, pointed it at the field, and saw what he thought was a big number, and freaked out, but that number is meaningless on its own.

Ask your AD if he has any logic to his decision, and if necessary, my reference is my B.Eng. in Chemical Engineering. Tell him I do this for a living. As you said, proper hydration and common sense will carry you through here. If it's stifling over the field and putting your hand to the turf is actually painful, either hose down the field (really easy solution) or modify practice a little.

I doubt your A.D. knows what he's doing. I was a technician for 5 years I know that those tools can be inaccurate if you don't use them right, especially the cheap ones.

I would show him that you can lay on the turf and be fine even if the temp reads 140f. And if it's too hot for you to lay on, then maybe he's right about not practicing on it.

Our field turf must have been 376 degrees today. Adapt and overcome. Build in plenty of water breaks (no longer than 20 minute sessions without a break). The human body can do amazing things, if hydrated.

Is it coincidence that we now have an ad for thermal imagers at the top of the screen?

I think that the AD is going the CYA route here, Hes gonna cover his a$$ because no one else will. With heat related deaths in football a very real concern for admins and the such I can understand where he is coming from. Engineer, Technician, whatever you are will not matter when it is someones kid that dies. I would cut the guys some slack, hes doing what he feels is right, as they say better safe than sorry.