Fart travel time depends on atmospheric conditions such as humidity, temperature and wind speed and direction, the molecular weight of the fart particles, and the distance between the fart transmitter and the fart receiver. Farts also disperse (spread out) as they leave the source, and their potency diminishes with dilution. Generally, if the fart is not detected within a few seconds, it will be too dilute for perception and will be lost into the atmosphere forever. Exceptional conditions exist when the fart is released into a small enclosed area such as an elevator, a small room, or a car. These conditions limit the amount of dilution possible, and the fart may remain in a smellable concentration for a long period of time, until it condenses on the walls.