I have found the following formula to calculate the expansion of air by a temperature change, if the pressure stays at the same level: ΔV = ɣ * V0 * ΔT
This would give me an expansion of 46.96m3 in a 4000m3 tank by a temperature change of 3K.
46.96m3 = 1/273 * 4000 * 3
Is there an influence of the air humidity in this calculation and if yes, how much is it and how to calculate it?
I would guess there is a small one since the water expands also somehow on a temperature change.