Wind chill: how to calculate? Is there such thing as wind warmth ?

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Discussion Overview

The discussion revolves around the concepts of wind chill and the potential for "wind warmth," exploring how air temperature and movement affect perceived temperature. Participants examine the roles of convection, evaporation, and humidity in these phenomena, with a focus on both cold and hot weather scenarios.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that if the air is warmer than the skin, it could transfer heat to the body, leading to a warming effect.
  • Another argues that evaporation from the skin significantly influences perceived temperature, indicating that wind can feel warm under certain conditions, particularly when sweating is minimal.
  • A different viewpoint emphasizes that the cooling effect from wind is primarily linked to evaporation and wet bulb temperature, suggesting that "wind heating" is not a recognized term in natural environments.
  • One participant questions whether wind chill encompasses only evaporative cooling or if it also includes forced convection effects, particularly in the context of a fan oven.
  • Another clarifies that wind chill is defined for cold conditions without considering evaporative cooling or clothing, and introduces Wet Bulb Globe Temperature as a relevant measure for hot weather.
  • A final comment mentions the heat index as a subjective measure that attempts to compare perceived temperatures in dry versus humid conditions.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of wind chill and wind warmth, with no consensus reached on the terminology or the conditions under which wind can be considered warm.

Contextual Notes

Participants reference various temperature measures and their applicability, highlighting the complexity of how different factors like humidity and evaporation influence perceived temperature. There is an acknowledgment of the limitations in defining "wind warmth" and the contexts in which these terms are used.

pa5tabear
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Wind chill: how to calculate? Is there such thing as wind "warmth"?

If it is really hot outside, and the air were warmer than your skin, would you feel warmer when it blows on you? Would there still be some sort of chilling effecT?

I'm guessing it's like basic convection. If the the fluid is warmer, the fluit will transfer heat to the body, and you will end up with some heating.
 
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I think the coolness you feel is just not described by convection. Evaporation of water from your skin also plays a major role in the temperature you perceive of air around you. The loss of heat through evaporation and gain/loss due to conduction together decide whether wind is cool or warm. So in principle, yes, you can feel wind "warmth". But only if you are not sweating profusely at that moment.
 


Almost. Because of evaporation, our bodies' ability to cool itself comes largely from sweat. So cooling amount is based on wind and wet bulb temperature. Wet bulb temp is based on dry bulb (normal) temp and humidity. There are no natural environments where wet bulb temp is high enough to cause a "wind heating" effect, so such a term does not exist. Even on a 110F day in Phoenix, your body can still cool itself -- better than on a 95F day in Philadelphia.
 
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But 'wind chill' doesn't only refer to evaporative cooling, surely(?). It must also involve wind speed (forced convection effects) against a dry clothed body.
Isn't it "wind warmth" inside a fan oven?
 


Wind chill doesn't include evaporative cooling at all...or clothes, for that matter. Wind chill is defined only for cold weather, when your skin is essentially dry. The nearest analogue for hot weather is Wet Bulb Globe Temperature (not the same as wet bulb temperature), which uses a formula to estimate the effects of ambient sunlight and wind on a wet bulb (you, in a sweaty tshirt) on a hot day.

Yes, wind heating is what happens in a convection oven.

Fyi, wind chill and WBGT both have good wiki pages.
 


Also, "heat index" (is one I don't like because it is purely subjective) tries to equate what it feels like on a dry vs a humid day.
 

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