Dear Friends:
June’s entry is an expansion of my monthly column (“Nature’s Note”) in “Sam News,” our in-house publication.
Space is always limited while my blogs are as long as my loyal webmaster, George Dumas, has the time and patience for converting my words into the WordPress format. It’s no secret that I am no fan of fog. But now with my declining eyesight, my world is enveloped in a perpetual haze and on foggy mornings we’re all in it together.
It’s only on the clear days that I know how much I’m missing. But at 93, I am every day grateful for a good mind and the ability to express and feel gratitude for what I still have.
It is through song and call note that I now recognize most birds. And I’m helped along by general body shape, where and how they are feeding and whether they prefer the ground or trees.
Even without my disability, it behooves me even if I don’t love fog, to at least learn to appreciate it by understanding how fog is formed and its likely behavior.
FOGGY DAYS
Today is June 1st. We are halfway between the two foggiest months of the year which locals call May Gray and June Gloom. When the prevailing northwest winds pass over the even colder ocean, the air condenses into tiny droplets producing the fog.
But it’s not as simple as that. In the northern hemisphere, the earth rotates counterclockwise (the opposite in the southern hemisphere). Because of this rotation, wind blowing from the northwest (our prevailing summer wind) curves to the right. As the wind curves to the right, it sweeps off the top layer of water causing the upwelling of the deep, colder water. When the relatively warmer wind passes over the cold, upwelled water, fog is formed.
This rotation, called the Coriolis Effect, has a profound effect on tides, bodies of air and even the behavior of storms. It causes our rainstorms moving in from the Pacific to rotate counterclockwise, so that the winds of an approaching storm, blow from the south.
Depending on the topography, fog can put on a dramatic show. In the Bay Area, fog building up like waves over the Sausalito Hills spills over the lee slopes. Unimpeded, fog moves like a river through the Golden Gates, the only complete break in the coastal hills. To the north and south the fog seeks out gaps in the hills as it moves inland.
When the fog enters the Bay through the Golden Gate part of of it aims for the Berkeley Hills. The rest turns left drawn irresistibly toward the heat and low pressure over the Delta and the Sacramento Valley. The fog is often accompanied by strong cold winds that are notorious in summer afternoons rushing through the canyons of tall buildings in San Francisco.
And there were those mornings in Berkeley when the fog stayed low and my hill rose above it like an island in a gray sea.
The fog varies in its extent. It can spread far out to sea. It can be a narrow ruffle covering just the beach or it can be drawn far inland by the warmer temperatures. It may flow at night into coastal valleys, and in foggier periods it will surmount coastal ranges, visiting even inland valleys.
Most days the fog will retreat offshore by midday, but other times the marine layer persists for days on end seriously depressing the spirits.
Meteorologists call this cloud type status. It’s usually made up of rather smooth layers of clouds that can sometimes meet the ground. The fog can either be “dry” or it can produce drizzle especially under trees, enough to register in a rain gauge. We need any moisture in this semi-arid climate of ours where longer periods of drought are a part of climate change.
Even though I seem to thrive on those days which begin with sun, I am now gratified, while still in bed on a windless dawn to hear the drip, drip of condensed fog falling off leaves and needles.
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Phila Rogers 