Monday, September 25, 2006

Wind chill

Wherein twelve Minnesota winters taught me the importance of layering

In 2001, the National Weather Service redefined wind chill. The new formula
Windchill (ºF) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)
T = Air Temperature (F)
V = Wind Speed (mph)
^ = raised to a power (exponential)

is interesting in a couple of ways. One, above 50 degrees, there's no effect. Two, the new formula is significantly "warmer" than the old; look at this NWS Chart:

Since google lists them first, this Wind Chill Calculator will dispaly old and new values.

On the bicycle I'd usually grab the leg and arm warmers for temperatures below 70º. With the scooter, and speeds around 45-55mph, it gets cold fast and a predawn ride in the low 50s had my fingers stiffening up. It's since warmed up again, but for morning I did dig out the glove liners and jacket liners making for a much more comfortable and almost toasty.

As a reminder of what to expect, here's a chart reflecting my anticipated winter riding conditions:


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