Saturday, January 26, 2008
The Sidewalk is Deadly
So, it's raining. Plain old Oregon rain, cold, but not a big deal -- except the temperature at ground -level is currently 28 degrees F., which makes for a nasty condition sometimes called a "silver freeze." (When it gets worse, they tend to call it an "ice storm." I'd never heard of such things growing up in Louisiana. First winter we were up in Oregon, we had one. Didn't look like much to me, so when I went out for my daily run of a couple miles, I stepped onto my driveway and promptly slid all the way to the street corner on my ass. At that moment, I decided to take up lap-swimming at the nice heated indoor pool instead of jogging ...)
If the condition gets bad enough, you just stay home. Snow-chains don't help, studded-tires, Yak-tracks on your shoes, nothing.
Unlike seeing great icicles hanging from the eaves as a warning, the first stages of this are deceptive. With the silver freeze comes black ice, a term that would be better called invisible ice. The sidewalks, being concrete with a higher albedo than asphalt, tend to ice over first, whereas the roads absorb more heat, such that it is. (Albedo is why a black car is hotter in the sun than a white one, though even dark material can reflect quite a bit of light. I have it that the surface of the moon has the same albedo as asphalt. Pretty impressive.)
Come the freezing rain, you step out onto the sidewalk, it looks fine, but of a moment, you find yourself skateless on an ice rink. Even so, you can keep your balance on the flats. But, if you come to a rise? Ice-skating uphill is a bitch.
When walking the dogs, better to keep to the ground. It gets crunchy, but unless the condition persists for a while, the thin layer of ice breaks as you walk upon it, and footing is more secure.
Which is to say, if you are in or around Portland, OR, today, and you need to go out, tread with care. The hip you save may be your own.