Science Frictions

Dark and Stormy Month

Now is the winter of our discontent, made bearable by the promise of sun

By Priscilla Long | January 30, 2013
Photo by Flickr user .anderson
Photo by Flickr user .anderson


This morning I’m at my desk beside the window, writing. It’s before sunrise, but not early. Here in Seattle, in the pit of the dark season, the sun rises late (at 7:45 a.m.) and sets long before dinnertime (at 4:20 p.m.). It’s chilly and cloudy and rainy. But mostly, it’s dark. Right now the sun is making a rosy glow on the horizon, not in the east but far to the southeast.

Leaves that were burnt orange and red ochre have turned brown as dust. Except for certain merlot-colored maple leaves wet on the pavement. The chaste tree out on the street, with its spear-tip-shaped leaves, has not turned to any fall color but has gone leaf-sparse and looks like lace. Many birds have gone silent or just gone. The crows are here though, blacker than black—black beaks, black eyes, black feathers, black feet.

Where did the sun go? Did it recede? Is it farther away?

Earth travels around the sun in an orbit that is elliptical, but not by much. It’s almost circular, so the sun stays more or less the same distance from Earth. This season business, this darkness, is caused by Earth’s axis tilting always in the same direction, about 23.5 degrees. Picture a top spinning, tilting at an angle. (The spin causes night and day; the tilt causes the seasons.)

Seattle is way far north, much farther north than Boston, for instance. Up here you can easily see how we are tilting away from that far cold yellow ball. In winter at high noon, it hovers rather low, 19 degrees above the horizon at winter solstice; in the late afternoon it sets not in the west but in the southwest.

Here’s a visual aid. At least it aids me. Your head is the sun. Take a pencil, tilt it up and hold it to the right of your right ear, pointing away from your ear. If you lived on the point it would now be winter. Now, without twisting the pencil or turning it in any way, pass it in front of your face and to the left of your head. Now the point is close to your ear and the eraser is far. Earth has traveled 180 degrees around its orbit. For pencil-point dwellers, it’s summer.

The Earth’s tilt explains why Northwest winters are so dark, but it doesn’t explain why sales of sunglasses are higher in Seattle than in any other American city (according to the Seattle Sunglass Co.). But I can explain that. During the long dark months, the sun may not come out very often or for very long, but when it does it gets right in your eyes.

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