Every time I take a shower, with no window open or fan on, the shower curtain?
liner rises up against my legs. What causes it to do that, since there is no air blowing into the bathroom?
Water flow stimulates air flow - so your curtain is reacting to the change is air pressure as water falls through the air.
Its because of a differnece in air pressure.
LOL funny question... I really don't have the answer but...I know is not funny ha? LOL
YOU ALREADY KNOW THIS ANSWER''
Bernoulli effect
http://en.wikipedia.org/wiki/Bernoulli_e…
Wind is air in movement. When you turn the shower on the air around the water starts to move. SO you do have some wind inside your bathroom even if your fan is off or windows are shut. So . I just would turn the fan on anyways and just check if you are buying good liners those who have the magnetic stuff in the bottom. Good Luck.