The shower-curtain effect in physics describes the phenomenon of a shower curtain being blown inward when a shower is running. The problem of identifying the cause of this effect has been featured in Scientific American magazine, with several theories given to explain the phenomenon but no definite conclusion.
The shower-curtain effect may also be used to describe the observation how nearby phase front distortions of an optical wave are more severe than remote distortions of the same amplitude.[jargon]