Wind chill!

There might be a risk of me sounding slightly obnoxious in this entry, so for all residents of Winnipeg - no offence! (at least not so very much ;)

The concept of what temperature is, seems to be getting a bit distorted in cold places like Winnipeg, since people tend to refer to wind chill number as the actual temperature. So, let us look at a few case studies:

- It's -20 outside, and no wind. You stand in the shadow, dressed in a parka, feeling comfortable. Why? Well, the heat of the body warms up a layer of air closest to your skin, and you're thus slightly insulated by this. Thus it actually feels warmer than it is and you don't feel the full -20.

- it's -20 outside, and a stern wind from the north is blowing. You complain, and pull the scarf tighter over your face, since you feel colder. Why? The wind is removing the layer of air closest to your skin, which makes the skin lose heat at a quicker rate, and thus you experience the cold stronger.

- You're submerged into a liquid that's chilled to -20 (obviously not water). Byebye.

All cases have a difference in pressure of the medium around you towards your skin. What changes is the rate in which you lose heat, not the actual temperature. You'll never get colder than -20 in any of these cases (which in all cases is pretty bad for the health, because -20 is pretty yuckily cold...)

- Common winnipeg misconception: It's -20 tonight but the wind chill is -40, I REALLY need to plug in my car! Well, yes, probably, because it's -20. It won't get chilled down to -40 though. It will however lose heat at a slightly quicker rate than if it wasn't windy, i.e. it might take 1 hour instead of 2 hours for the car to get cold after it was driven (never below -20 though!). Since you're probably staying in bed for longer than that during the night, it won't make a difference at all to you.
Thus, if it's -10, and a really nasty wind, your car will most likely start in the morning anyways, regardless of if it's plugged in or not (but you will still be complaining as you fight your way through the wind to the car, struggling with the keys to unlock it and rightly so, because it's MARCH and should be SPRING ugh...)

I had an interesting experience a few weeks ago, waiting for the train in Sydney. It was +41 outside. Sitting still, my body kept me chilled, but when the wind blew at me, it got really hot. the "wind heat" dried up my chilling sweat layer, and made me feel the real temperature (+41 is really hot...), but it didn't make it any hotter than +41, just as the wind chill doesn't make it colder. It's just your perception that changes due to the rate with which your body is being affected to the surrounding temperature.

(Then we have the extra wind chill you can add on someone who's spent 5 weeks in Australia, and comes back to Winnipeg - take off at least anouther 10 degrees! It took me about a week to get used to the cold again, and the time inbetween was terrrrible, I've never had so much pain walking to the bus in my life!!)

I can understand that it is important to know how quickly you will chill off in the wind, and I can agree that using an "equivalent temperature" gives a pretty good idea. What I don't like is how easy it is for people to misunderstand it, and think that it actually is colder than it is. The meteorological sites purposely don't use units on their wind chill estimates, to emphasize that it's not a real temperature.

Bring it on...