Koma, As PWP notes, the changes that you're discussing - checking the pressure of the balls & compensating for the temperature changes that happen during a game - represent a real change to the way that the balls have been prepared for a century or so.
This is a bad course to take. And there is no reason to do so.
A quick & easy calculation shows that the misguided effort of the league official to re-inflate the Pats' balls at halftime during the Pats/Colts game resulted in over inflated balls for the 2nd half. The balls that the Pats used during the 2nd half of that game were EQUIVALENT TO balls that had been pressurized at 75°F to 14.6 psi.
This condition was obviously not the Pats choice, but was forced on them by league officials, who were ignorant of simple gas laws.
You DO NOT want to take this path.
The pressure drop in the cold that makes the ball slightly softer is actually counteracted by the increased stiffness of the leather in cold weather. As it is now, in really cold temperatures, they describe the ball as being "hard as a rock". This tells you that the increased stiffness of the leather overwhelms the decreased stiffness due to the lower pressure. If you now go back to re-pressurizing cold balls to 13 psi, then the balls will become significantly harder still.
For example, at 0°F, a ball that is inflated on the field to 13.0 psig is EQUIVALENT TO a ball that was inflated in the standard way that we've been doing it (i.e., at room temp, let's say 75°F) to 17.5 psig. This is a drastic difference.
There is a simple process to address this. It merely requires the measurement of the temperature inside the balls when they are being inspected. Then you look up the allowable pressure range on a chart that shows you the proper temperature compensation.
This approach is easy, non-intrusive & the measurement has to be done only once.
As 2nd side benefit is that - under the current system - there is an easy way to cheat the system. If you want stiffer balls (like Aaron Rodgers), you use cold air to inflate them. If you want softer balls (like Brady), then you use hot air. Measuring the temperature of the air inside the balls eliminates this loophole.
With this chart, one can also check the inflation state of the balls at any time, and at any temperature. If one side squawks the other side's balls, the refs would be able to immediately check the balls at any time during the game, at half time, or after the game, etc., and know whether they had been tampered with. More important, the refs would know the exact right amount of air to put back into the balls to return them to the proper inflation state, and not repeat the half-time inflation error that happened during the Pats/Colts game.
Right now, it is not possible to do this, unless the game is being played at right around "room temp".
But, hopefully, this lunacy will never again darken our doorsteps.!
The key is this:
The inflation state of the balls depends on BOTH the pressure & the temp of the air inside the balls. If you don't measure both, you have no idea about its inflation state.
To date in the NFL, the "inflation state" has been inadequately defined, because the temperature inside the balls has never been measured. The unstated, uncontrolled assumption has been "13.0 ± 0.5 psig, at some undefined room temperature". This ain't good enough once you start to try to measure the inflation of balls significantly above or below this undefined temperature.
