ok,its about -30 C outside and the weather forecaster says with the windchill it feels like minus 45 or whatever, makes me wonder just how do you measure "feel"? Please Register or Log in to view the hidden image!
A function of wind speed and temperature. When the wind blows, it removes the thin protective layer of warm air (from body heat) surrounding your skin, making your skin feel colder than it really is. This is the same phenomenon as blowing on your spoonful of soup to cool it down. You're blowing away that top layer of warmer insular air. Interesting to note, wind chill doesn't affect objects. You can't say, "My car starts fine when it's as low as 0 degrees, but since the windchill is -20, my car won't start." It's all to do with "feel:" perceived temperature as opposed to actual temperature. I suppose your point being, how do you measure that "feel," here's a scale and some info.... http://www.nws.noaa.gov/om/windchill/index.shtml
No chunky, your wrong. Winchill can affect objects. The right thing to say is that it can't affect things of the same temperature as the environment which is most things....but not your car. A cars engine will be cooled more significantly in a wind or in rain than when it is calm and dry.
It will cool more quickly, yes, but if you placed a thermometer on your engine block after driving, would it read cooler if the wind was blowing on it than if it weren't? My inderstanding is that the whole windchill factor thing corresponds to how you perceive the temperature to be, relative to wind speed. It is based on a human face model, and uses skin tissue resistance as on of its measuring parameters. An engine can't feel.
Absolutely not. Wind chill factor has nothing to do with our senses changing at all. We are still measuring the right temperature but that temperature is lower than it would be if there were no wind (or rain). Also the windchill does not depend on this breaking of the warm barrier alone (in fact this is only minor). Most of it is caused by evaporation on the skin surface. This is why it is colder when its wetter too. Our temperature sensors are near the skin surface.
This from a page from nasa.gov: Any warm object, like a human being, will lose heat when it is exposed to cold air. The greater the wind speed, the faster the object will lose heat. The difference between people and inanimate objects is that we feel or sense the heat loss. A temperature we feel is called a sensible temperature. Maybe you've noticed that some days feel colder than others when there is a strong wind blowing, even if the temperatures are the same! This phenomenon is known as wind chill. To estimate the heat loss based on temperature and wind speeds, we use the Wind Chill Index. Wind chill is referred to as an equivalent or sensible temperature, since it is not an actual temperature.
OK I think this a semantics thing then. I agree that the temperature of the object does not change significantly from environmental temperature (in some cases - see below) but what we perceive as being cold isn't temperature either. It is heat loss rate. All objects CAN experience elevated heat loss rate due to wind or rain (but mainly humans because of their 'wet' skin and heat production) but in say animate objects, this affects the temperature of the skin. Skin temp will be lower in wind chill conditions than in calm conditions and this can also happen to any objects which produce heat. Such as your car engine!
The semantics is what I was getting at. I was not disputing anything about heat transfer of an object. Just that "windchill factor" as a weather term has to do with a human model and sensory perception. That is all.
OK but its important to remember that the factors which cause 'windchill' also affect any inanimate objects which produce their own heat and if they could feel this elevated loss of heat like we do then they would! Any inanimate objects which don't produce heat would not 'feel' anything because they would not be losing any more heat after reaching an equilibrium temperature with the environment. A lot of people forget this so this is what I was getting at!
