Also, it depends on the mixture of gases in the ball. Add a smigion of low vapor pressure gas (H2O for example) and you could get the pressure drop at 45 degrees.
You are full of good ideas !
True that. Wet air could give a similar result.
You have two approaches there.
1) Condensation
2) Adsorption
You could pick a gas that will condense a the field conditions.
You could pick a gas that gets adsorbed into the football.
Hmmm. We could even pick a gas that is hard to contain. That it easily permeates through the football. Such as a small touch of Hydrogen perhaps?
Basic gas laws.
Volume remains constant.