Charles' Law
“For any gas at a constant pressure, the volume of the gas is directly proportional
to its absolute temperature.” – Jacques Charles
V1 / T1 = V2 / T2
V and T are volume and temperature.
This formula expresses the relationship of volume and temperature at constant pressure. Directly proportional means when one value changes, the other value changes at the same rate. Charles’ Law represents how volume will increase when heated or shrink when cooled. When the temperature increases volume will increase, if the pressure stays the same; conversely a decrease in temperature will lead to a decrease in volume.
In a balloon, gas molecules hitting the inside of the balloon keep it inflated. A balloon will increase in size when the temperature of the gas inside increases, the balloon expands. The gas molecules moving faster strike the wall of the balloon with more force, causing the balloon to expand.
This laws explains an interesting phenomenon that occurs when a dry suit diver emerges at the end of the dive, and air temp. is colder than the water temp.
Due to the decrease in the suits’ gas volume, the diver can become “vacuum sealed” in their suit. Divers add air to the suit from their tanks, or unzip the suit, to release this “squeeze.”