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Lynn Lau
Northern News Services
We've all heard people from the wet coasts complain about "wet cold."
 Cold? What cold? Reporter Lynn Lau, fully acclimatized to the weather in the Arctic. - Malcolm Gorrill/NNSL photo |
Is all that wet cold vs dry cold a load of hooey or what?
According to University of Alberta cold expert Bob Christopherson, there are many other things that can affect our experience of cold, including humidity.
Damp air conducts heat energy more efficiently than dry air, but the wet cold theory falls apart at around -15C, when all cold is more or less dry cold.
"It's never humid when it's -30C," Chistopherson says. Cold air doesn't hold much moisture, so although the relative humidity may be high, the actual amount of water in the air is minimal.
Aside from humidity, other weather conditions also affect how cold we feel. Every heat source chills down in three different ways -- convection (as in windchill factor), conduction (think cold metal bench), and radiation (what happens whenever you expose yourself to the atmosphere).
The more heat you lose in any of these ways, the colder you feel.
Radiant heat loss, for example, explains why -30 C on a starry night feels colder than -30 C on a cloudy night. On the cold clear nights, Chistopherson explains, the temperature gradient between the sky (which might be -80 C) and you (+37 C, we hope) is much greater. That means your body loses heat faster.
"If there's a low cloud cover on a cold night, the radiant energy hits the cloud and it acts like a roof."
Finally, another important factor is how weathered you are before you experience the cold. Animals and humans both adapt to cold weather, Christopherson says, and in cattle, it takes three to four weeks to adjust. In humans, it may depend on how much time you spend outside.
It appears that if you tough it out, you'll end up tougher in the long run.
