Fog Blog

Inland: Blue skies, a scattering of cumulus humilis, ripening grapes viewed from atop a glacial erratic near McMinnville, Oregon.

   I had heard rumors about the late-summer fog pattern (thick, persistent) along the Pacific Coast beaches, but got to experience it first hand a few weeks ago in Oregon. We had picked up friends at the Portland airport on an 90+-degree day and headed southwest through the beautiful and sunny Willamette Valley (above) toward the coastal town of Neskowin.

  We knew our rental house didn't have a view of the beach, so before checking in, we drove a little ways past the house to get a lay of the land. What we got was the lay of the fog (below) over every inch of ocean as far as the eye could see. Can you hear the sucking sound of the warm, inland air?

   

On the coast: a sunny day above, but not on, the beach at Neskowin.

  What is happening here is this: The lovely, hot, and harmless looking air we enjoyed in Portland had been rising during the day. And as the hot air rises, it creates a kind of vacuum quickly filled by the surrounding air around it at ground/sea level. As the warm air lingering over the ocean is sucked inland, it passes over the relatively cooler water and condenses. The condensed water vapor becomes visible water droplets--fog. This type of fog  is called advection fog. This type of fog forms when warm, moist air is carried horizontally across a cold surface by a wind of about 6-10 mph. This gentle wind is responsible for carrying the cool air and fog to greater heights along the coast. According to the Encyclopedia of Weather and Climate by Michael Allaby, advection fog can be 2000 feet deep.
   Advection fog is "world famous" for its photogenic presence around San Francisco's Golden Gate Bridge and for making Cape Disappointment, Washington, the foggiest place in the Lower 48.

Advection fog created this lovely Coppertone-free afternoon at the beach for my friend, Mary.

We lingered a while on the beach, watching the fog take over the beach like it owned it. It was quite a show, the highlight being my first-ever fog bow (below).

Fog bows appear as albino rainbows.

  Fog bows form under certain conditions: the water droplets in the air must be very tiny--less than .05 mm--the size of droplets of this fog. The sunlight is reflected, refracted, and diffracted by the droplets in such a way as to create white light. Larger water droplets (rain droplets) in the air separates sunlight into the classic ROY G BIV-colored rainbows. 

Here my friend, Kevin, looking for the pots of white gold at the end of  the fog bow.

   To see these fog bows, the sun has to be shining from directly behind you and into the fog. We did this for a while, then turned toward the ocean to see what appeared to be several layers of clouds moving rapidly inland. The fog was sliding in just over the water, and a thick, gray bank of clouds (I am thinking stratocumulus) were forming well offshore and condensing further into altocumulus as they floated up over the warm air, bluffs, and interior hills that rose to 1500 feet in less than 2 miles.

Proposal Rock could not steal the show from these advancing clouds.

The clouds seem to float on a layer of invisible warm air once they encountered the land. The receding tide may have had something to do with the cloud pattern.

After the sun set and the inland air began to cool, there was less air moving inland and therefore, less fog blanketing our beautiful coast line (below).

This cloudscape could almost be a painting were it not for the awkwardly placed and uncroppable tree.

   The following day was as dramatic but with more blue sky. A perfect day for a gourmet picnic featuring a dessert I knew from my East Coast childhood as "Twinkies." I probably would not have bought these at the Neskowin market had they not been renamed. They were, like the clouds and the company, as fabulous as ever.

Still Life with Fog

   I went outside Friday morning to watch the magical progression of this dense fog. I lingered, I loitered, I stood in the wet grass, I watched the geese, I tried to be still. At one point the only sound I heard was the dripping of the fog onto the bigleaf maple leaves. The fog--ground-level stratus clouds--lifted over a period of three hours. I watched them rise into the blue sky and transform themselves into cumulus clouds.

   I passed a man on the bike trail, dressed head-to-toe in camouflage. He was walking his small collie. He said, "Isn't this beautiful? You could say that you are walking in a cloud." I agreed and said I would.

   The fields were full of restless geese, rising in a panic, honking their way across the gray sky.

   

 Wouldn't this be something to surf?

And here, the fog rising and dissipating in the sun-warmed air. What a morning!

The Subtle Clouds

The day dawned foggy on Tuesday. These are steaming rooftops of homes just off Boulevard Road. Fog is a type of stratus cloud and morning fog in Olympia usually portends a clear day. While billowing culumus clouds capture our attention most often, the lowly stratus clouds and the very high icy cirrus clouds often get neglected. Some clouds are fun to spot, these types are fun to watch over a longer period of time. They are quite dynamic, but you have to sit still to enjoy them.

  

This is also fog (above) rising as the sun warms the air around them. I couldn't resist an end-of-season ride in the row boat. Here's a lingering bit of fog at midday on Budd Inlet (below).

                                     
 

And then, in the western sky, a dazzling show of cirrus (below). These are high-altitude clouds (16,500 to 45,000 feet up) and are composed of ice crystals.

 These are cirrus uncinus--small clumps of ice crystals being blow about by winds aloft. The heavier ice crystals fall behind and leave a trail like a comet's behind the main cloud.

Fog Blog

What a glorious spate of weather, so beautiful that it is almost heartbreaking. After our unremarkable summer, every moment of these autumn days presents something to write home about. For these days, I believe, we have the fog to thank. October, according to meteorologist Cliff Mass, is the foggiest month in Olympia. To celebrate, I am posting this fog blog--some photos, some science, some encouragement to trying to enjoy the lack of horizontal visibility that this type of stratus clouds brings to the landscape.

Last September, as my devoted readers may recall, I went swimming in the fog early one morning when Ward Lake was all but invisible. This year, the scene was the same (above), but I decided to photograph the fog moving over the city rather than swim in what was hanging over the lake. So I went up to Overlook Park in Tumwater with my camera. A water tower (below) marks the hilltop location of the park; this is the only time I have ever seen the color of the sky match the "camouflaging" paint color of the water tower. This is the view to the south.southeast. 

And this (below) is the view to the north./northeast Just to the right of the large tree is the ghostly capitol dome. . The fog was rolling in from the northwest. The photo below was taken at 12:15 p.m

 

This one at 12: 39 p.m.

This one at 12: 48 p.m.

  

And this one at 1:03 p.m.

   Fog is precipitation, formed of tiny water droplets, that takes the form of a stratus cloud--one that is in contact with the ground and that reduces horizontal visibility to less than 1/4 mile (1 km). If you went outside early in the morning this week, when the fog was the densest, you could see the individual droplets of the fog and watch them moving and swirling and falling.

   There are many types of fog--ground fog, ice fog, frozen fog, freezing fog, fog smoke, sea fog, Arctic sea smoke, Bora fog, steam fog, valley fog, caribou fog (caused by warm exhalations of herds of caribou!), frontal fog, upslope fog, advection fog, and radiation fog. I could go on...

   But let's talk about radiation fog. This is what we are experiencing in Olympia now. This type of fog forms on clear, cool  nights (you have been seeing the stars and moon, right?) and usually after a sunny day during which the ground absorbs the solar heat. At night, that heat radiates from the ground into the air; the ground cools sharply after this loss. The warm air radiating from the ground comes in contact with the cooler ground. The water vapor in the air condenses and creates visible fog. A whole night of this and the fog builds into a thick layer that rises over the treetops. 

  Why does the fog hover over Ward Lake and other area water bodies? Two reasons. Our lakes are located on low ground and fog, which is heavier that the surrounding air, settles in low spots. And, because Ward Lake itself is radiating it's summer's worth of trapped heat into the surrounding air. I like to imagine the lake's fog as its slow release of summer into the crisp fall air. As long as there is fog on the lake, I know the water is still warmer than the air. In November, the water temperature is closer to the air temperature and the dense fogs are mostly gone.

  Here is a wonderful illustration of radiation fog by my favorite American author-illustrator-meteorologist-painter, Eric Sloane. This is from his 1952 Weather Book (a 2005 Dover reprint). He's my hero.

   And, finally, because I had heard than rain was in the forecast (putting an end to morning fog), I went out my favorite really low spot--the Nisqually National Wildlife Refuge. I was hoping to find myself wandering around for hours looking for my hand in front of my face, being attacked by Canada Geese I tripped over, or falling blindly off the dike and into the muck but, alas, I was too late for such Accidental Naturalist fun. I did get to enjoy the thick fog hovering over the still-warm waters of McAllister Creek (below) at low tide. The photographs show the long boardwalk (under construction) that will take visitors half mile out into the estuary. Click here for info on the refuge and for news about the new boardwalk opening.

 

"It usually takes a rainbow, a thunderstorm, or some of of atmospheric antic to make us look upward and take note," writes Eric Sloane. "But if that gives us the habit, it is worth while. And I'll wager you will see a lot up there that you never dreamed of."