Common datum

Abstract

The air we exhale is 100% saturated with water. The air in the lungs is essentially saturated with water at 37 C, which is about 44 mg/liter. The average lung capacity of an adult is about 6 liters. Once exhaled, the air cools to the ambient temperature, leaving the air supersaturated. If it is cool enough it will form a visible cloud. When our breath comes in contact with a cold surface, it will leave visible condensation.