The "wet bulb" is a device that takes into account air temp, humidity, and wind speed, in order to calculate a heat index score. When that score reaches a certain point, we have to take off shoulder pads. If it reaches the next level, we have to take off helmets. If it reaches a third level, outdoor practice is over.
In Georgia, it is only used in practices, not in games. The theory as to why it isn't used in games is that players have more breaks, the action isn't as continuous, they take their helmets off more, etc.
Officials don't see it (or in some cases even know about it) because it is just one more of those things that a coach has to know about, but isn't a game issue. I'm really not saying this is a smart IDIOT way, but there are MANY things coaches have to manage all week that officials never see. Contact restrictions, wet bulb readings, number of quarters played by each player each week, filing practice plans for the state, etc.
I'm not complaining, it's part of the job. But a coach has to be an accountant, a lawyer, an equipment expert, a meteorologist, and oh yeah, a mentor, in some cases a father figure, and that's before we get to actually coaching football.
So if some are a little cranky on Friday nights and don't know all the rules as well as you would like, well, it's because they were working on a LOT of other things!