Monday, June 18, 2007

That wonderful time of year...

Some people hate it, some love it. Usually the ones that don't care for it move away at some point. It's summer time in San Francisco and that means .... fog.

I love it. It's a natural air conditioner. When I spend most of the day in other parts of the Bay that don't get the fog it can be well into the 90s F. And then I'll travel 20 or 30 miles into SF and it'll be in the 60s. In addition to the cooling aspect, I think it is beautiful to watch and seems to add drama to what would normally be a typical boring day in modern life. Plus, I have to admit, I do get a kick out of tourists who come to San Francisco in the summer expecting it to be like southern California. They are in shorts and short-sleeved shirts standing on top of Twin Peaks while its 55 degrees F and rather blustery. Tough break...shoulda brought a jacket.


Why fog in the summer?The graphic above is from a San Francisco Chronicle article a couple years ago (click on image to see the full story). Depending on how thick this marine layer gets, the fog will blanket more of the Bay Area. Since San Francisco is at the outlet to the ocean (Golden Gate), even a weak/thin marine layer will create some fog. On other occasions, the marine layer is thick and robust and can overtop the Santa Cruz Mountains to the south. And other times, the inland valley will be so dang hot, that it just sucks that fog right up the Sacramento delta and river.

Once in a while you'll get this very low, ground-hugging type of fog that has a very sharp upper boundary. It's usually when its rather windy too so it's moving along pretty fast. I'm writing this post because that's how it is this afternoon. I wish I had a nice video camera....it is quite spectacular. We live on the lee side of a major set of hills, so the fog is cascading over the side like a waterfall of fog...a fogfall I guess.

I guess I don't need a video camera....amazingly I found one on YouTube that shows this type of fog at the same general location.



That one is a little dark. The video below is from nearby (Sausalito) and shows the cascading fog much better.






photo above from here

2 comments:

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Katie said...

I like checking out the LHS time-lapse movies (they have some good ones archived) to watch the fog come and go -- even at night. Check them out from berkeley....

http://scienceview.berkeley.edu/view/