A measure of the increase in the instantaneous density at a given point owing to a sound wave, namely (ρ-ρ₀)/ρ₀, where ρ is the density and ρ₀ is the constant mean density at the point.

Transformation from a gas to a liquid.

See <<Bose-Einstein condensation>>

An increase of electric charge on a capacitor conductor.

An increase in density.

The process by which water vapor becomes a liquid such as dew, fog, or cloud or a solid like snow; condensation in the atmosphere is brought about by either of two processes: cooling of air to its dew point, or addition of enough water vapor to bring the mixture to the point of saturation (that is, the relative humidity is raised to 100).

Focusing or collimation of light.