Last night I had to change propane tanks on the fly, and noticed that the empty tank had some ice formed near its base. This is despite the fact that it was connected to a hot barbecue on a warm summer evening. Here’s what it looked like:
As you use the tank, the pressure inside goes down. As the pressure drops, the temperature also drops because of something called the Ideal Gas Law. Ice forms on the tank because water moisture in the atmosphere is condensed on the cold tank and then frozen.
Would anybody care to elaborate?