Higher Order Math & Handling Ice

Tuesday's rain washed away much of the snow. The white line is visible along 95% of the road. Finally back on the bike commute this morning! Mid 30's warrants boots, tights, and gloves, but no need for chemical heat packs.

Students of radiant heat transfer understand that even though the air was above freezing all night, there are still thin layers of ice on the road in the morning after a cloudless night. Why? Because outer space is essentially an empty vacuum and thus it is absolute zero , i.e., -460 Fahrenheit. Cold enough so there is no molecular motion at all. How cold is that?  It's 360 degrees colder than solid CO2 a.k.a. "dry ice".  Stupid cold.

Engineering Stuff:
Any two objects that face each other exchange heat with each other through radiant heat transfer. Heat moves from the warmer thing to the colder thing. This is why you get warmed up when relaxing on the beach. This is how solar hot water heaters work. The sun's surface is about 11,000 Fahrenheit. It sends out its heat uniformly in all directions and a tiny portion hits the surface of your skin or a solar panel. The same heat exchange happens to water on the road. Except the water is the warm thing and the blackness of empty space is the cold thing. Without dragging you through nasty derivations, radiant heat transfer isn't a big deal when two things are similar in temperature. It comes into play when things are really different in temperature (because it relates to the fourth power of the absolute temperature of each object).

Executive Summary:
Water on the road can give up enough heat to freeze during a cloudless night even when the air temperature is above freezing.  EXPECT ICE.

A few comments about riding when there's ice:
* If it looks like a puddle, expect that there's ice under the surface. There's nothing with less friction than ice -- except ice with a thin layer of water on it. Too much experience here.
* If you have to ride across ice go straight. Don't accelerate. Don't decelerate. Don't turn.
* If you have to ride across ice, you may be better off speeding up before you get to it and zipping across. I've had this work a few times. I've crashed doing this, too. You don't want to do that in traffic.
* Your balance is better with a lower center of gravity. Relax your muscles. Lower your body, get your tail off the saddle, and put most of your weight on the pedals while maintaining gentle control of the handlebars. Allow your elbows and knees to flex.
* You don't have to ride across ice. You can ride around. You can walk.
* Stay focused and alert. As soon as you see a patch of ice, look ahead and in your rear view mirror. No cars? Ride around it. A mess of cars coming? Slow down or stop and let them pass. That's okay. It's not a race. You have all the time you need to get there safely. When the road is clear, you can walk across, walk or ride around the ice.
* If you want to bicycle on ice and snow regularly with confidence, there are studded bike tires. They're a bit expensive and I wouldn't get enough use to justify them. They're heavy, they're noisy, they wear down, and require extra effort when pedaling. But they work!

Ride well!