Water in snorkels

While driving through rain if you hold a paper cup horizontally out of your car window (facing forward) you will find that it collects a lot of water. So could someone explain to me what happens to the water that enters a snorkel intake under the same circumstances ? I found a string in the archives about snorkel intakes facing forward/back/sideways/revolving and I don't want to get into all that again, but in that string someone suggested that the water hits the back of the intake then runs out through the join. I would have thought that if the intake is fastened on fairly tightly only a small amount could escape that way. I also found mention of a trap in the air filter box, but that would presumably be of a finite size and would eventually fill.

Anyone know the answer?