A natural occurring phenomenon where the cool water of the Pacific Ocean evaporates and transforms into clouds; usually dense, low to the ground clouds which we like to call fog. Depending on where you live this fog, or Marine Layer, will roll onto shore in the late afternoon. It hangs around all through the night until morning when the sun heats up the earth, making the warm air rise, either evaporating it or pushing the cooler air of the Marine Layer back out to sea.