The Atmos is a clock from the Jaeger LeCoultre stable, designed to be in harmony with nature, it took the concept of perpetual movement to the next level. It uses slight variations in temperature to power the clock.

The exact mechanism of the barometric/temperature sensitive power source is delicate but not complicated. There is a bellows which consists of a flexible metal capsule filled with an inert gas and a few drops of ethyl chloride, which boils as the temperature becomes warmer, causing the bellows to expand, and vice versa. As the temperature warms to about 75ºF, the bellows expand, which winds the mainspring. The bellows are also affected by changes in atmospheric pressure, which is why this is called the "Atmos" clock.