Wrapped in a shroud of cloud: Our winter coat of gray has a silver lining
Seattle Times staff reporter
From now until July, we are in the company of vapors, scribbled skeins of mist and murk.
The Earth is tilting from the sun, the jet stream snugs in close, and that great chiller, the Pacific Ocean, is working overtime, manufacturing clouds.
There are 228 cloudy days in a typical year in Seattle, compared with 133 in New York City and 117 in Miami, according to Cliff Mass, an atmospheric scientist at the University of Washington.
For some, this is our season of discontent, a time to get out of town, stay in bed; a gut-check time to ponder that move to Phoenix.
But there are those who revel in this, our season of clouds, with its soft silvery light and the sigh of fir and cedars in the rain.
It's that fuming sky, wild as a child's drawing, that drives away the tourists, after all.
Clouds are the machinations of the atmosphere made visible, the ephemeral offspring of our geography. Born over the vast, cold Pacific, the clouds are trapped here by the bared teeth of the Olympics and Cascades.
The overhead parade is not random, but made of three basic cloud types: cumulus, or heaped clouds; stratus, or layered clouds; and cirrus, or wispy clouds. Temperature and altitude determine their life span and form.
And while they look serene, clouds are actually maelstroms within. Vortices of turbulence inside each cloud spin out water droplets, slinging them free as rain or snow.
We have a skewed vision of clouds here, always equating them with rain. But only about 1 in 25 clouds actually spit rain — most evaporate, says Robert Charlson, professor of atmospheric sciences and chemistry at the University of Washington.
Clouds form on tiny atmospheric particles such as salt, dust or smoke. Very polluted places often have more fog and thicker cloud cover that takes longer to dissipate — a threat to agriculture in places with truly filthy air, such as parts of China.
Clouds also contain information: Each is a clue to what's coming next. The storms that seem wild actually have an orderly progression.
First come the wispy cirrus clouds, high and delicate.
Next comes cirrostratus, producing a halo around the sun or moon.
Next comes a scrim of gray — altostratus — that covers the sun or moon, creating a milky glow.
Then comes the thick, lowered brow that threatens rain: stratus and stratocumulus — wet, full-bellied and ready to rip.
Wind follows and the clouds blur. Their wet world engulfs us, and the rain marks us as creatures in the care of cycles bigger than our own.
The clouds shred and break, and sheets of rain shine in defiant shafts of sun amid teases of robin's egg blue. Rain-slicked roofs steam in the sudden brightness, just as quickly snuffed as another raft of gray muscles in from the sea.
Lather, rinse, repeat.
It's nature's own growth management act, nine months of gray, count 'em, November through mid-July.
Observations taken every three hours by the National Weather Service at Seattle-Tacoma International Airport from 1948 to 1990 confirm that in November, the sky is overcast 65 percent of the time, on average. January? Try 68.8 percent overcast. Not until May do we crack the 50 percent mark.
We have a lot more gray than we do rain. Miami, Boston, Atlanta, New York and Houston all get more rain than our yearly average of 38.27 inches at Sea-Tac.
The difference is, they get it over with. We drag our rain out over months of drizzle, leaked from a lid of gray.
Lynda V. Mapes: 206-464-2736 or email@example.com. Natural Wonders appears every other Monday.