Marine Layer vs. Fog … that is the question
So, why is called a marine layer and not fog in Southern California? I’ve been wondering why ever since I’ve moved here 4.5 years ago. I realize the definition of marine is “of or pertaining to the sea.” However, wouldn’t that also be applicable to San Francisco? Granted SF sits on a bay, not the ocean, it is ocean water though.
Yes, I’m being serious when I ask this question. Yes, I drive people nuts with my “only you would wonder that.”
Throw a girl a bone.

This was the best photo I could find, of mine, that kinda represents a marine layer.
Would you believe there is a Wikipedia entry on this?
http://en.wikipedia.org/wiki/Marine_layer
Huh. How about that. I, quite obviously, was mistaken that they were one in the same. Thanks Gina!
So, technically, the “Marine Layer” we all talk about is technically the “fog” trapped in the “marine layer”, because we’re constantly referring the the gray crap that blocks out the sun and makes June lame for SoCal. That settles it, I’m calling it fog from now on!
To me fog=clouds on the ground. So when you’re driving, and you can’t see everything in front of you, that’s fog. The marine layer is just overcast skies. Whatever it is, I love the marine layer in the summer. Drove out to the San Fernando Valley last Sunday night, and it was freakin’ hot. So nice to get back to Santa Monica and the marine layer.