Talk:Wind chill

From Wikipedia, the free encyclopedia

WikiProject Physics This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
Start This article has been rated as Start-Class on the assessment scale.
Low This article is on a subject of Low importance within physics.

Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.
This article related to extreme heat or cold is part of the temperature extremes sub-project of WikiProject Meteorology and weather events, an attempt to standardize and improve all articles related to weather or meteorology. You can help! Visit the project page or discuss an article at its talk page.
Start This article has been rated as Start-Class on the assessment scale.
Mid This article has been rated as Mid-importance within WikiProject Meteorology.

Why does the V overlap the 0 in the formula? Rmhermen 14:25, Aug 14, 2003 (UTC)

Contents

[edit] For what range of values is the formula valid?

The wind chill formula seems on the face of it to only be valid for certain range of values. E.g., it seems strange that when V=0 it doesn't reduce to the ambient air temperature.

Also, doesn't wind chill apply in other circumstances such as when riding a motorcycle? For this situation rather higher temperatures and velocities might be interesting. Does this same formula apply. And if the effect is mostly related to evaporation, what effect does clothing have on the perceived temperature? -- Jake 21:45, 9 May 2006 (UTC)

E.g., if you google ("wind chill" motorcycle) there are other formulas that seem to be used. How do they relate? Jake

Well one thing I am interested in is the wind "chill" at higher temperatures. I ride a motorcycle and as most of the riders out there can tell you over about 90 or so degrees the felt temp increases with speed. Does anyone have a table for that?71.112.83.24 01:33, 12 July 2007 (UTC)

If you simply put the wind chill equation on the wind chill chart in the article into a spreadsheet, you will find that the equation explains the increase of temperature. When the temperature is over 60 F the wind causes the "real feel" temperature to increase; the increase is nearly imperceptible though, less than five degrees F until the temperature is over 90 degrees F.
As for the invalidity of the equation at V=0, the equation is written assuming that there is a wind, because without a wind, the concept of wind chill is irrelevent. When the wind velocity is zero, several of the assumptions made in deriving the equation may no longer be valid.
Clothing does make a big difference in wind chill. The type of cloth is important as is the number of layers. The cloth creates a barrier which decreases the wind speed that contacts your skin; the more it can decrease the wind speed the less wind chill you will feel. Yesterday, the actual temperature was -50 degrees F with a wind speed of 25 MPH, creating a "real feel" of -91 degrees F on Alaska's north slope. With my coat open to the wind, the real feel was unbearably cold; however, with the coat closed to the wind, it was bearable. (-91 degrees F and people are talking about global warming? send it my way). —Preceding unsigned comment added by DWL37 (talk • contribs) 19:01, 16 January 2008 (UTC)

[edit] Skin, "feel like"

In the first sentence of the article, it is claimed that skin is the only relevant thing that can feel wind chill, but later it is mentioned that it can apply even to inanimate objects, albeit with different formulae. Is the latter correct?

In a similar vein, the warning at the end seems to be sort of POV—the clause "but 32 °C can correctly be said to feel like 32 °C only at 0% humidity" is neither patently obvious nor supported by a citation. Indeed, it seems quite incorrect. Thoughts? /blahedo (t) 00:34, 1 August 2006 (UTC)

i would disagree that it's not obvious. the idea they're trying to get across is that, if you are at 32 °C with x humidity, then what you are actually feeling is temperature+humidity. to feel only the temp, you would need to remove the other variable. in practice, charts/graphs would perhaps be more effective if they were based on some avg humidity, but that seems to me like it would muddy the concepts. for the same reason, i don't like the benchmark wind-speed idea in the article. if you look at a painting through sunglasses, you don't know what the colors of the painting actually look like, you only know what they look like filtered through the dark lenses. --dan 07:38, 30 November 2006 (UTC)

Wind chill cannot apply to an inanimate object. There are no exceptions. Humans (and Americans in particular I think) always anthropomorphize. Eric Jensen

Wind chill can be applied to an inanimate object, as long as the definition of skin is not limited to human skin. Wind causes the moisture on an object to evaporate, and the evaporation process removes heat from the surface on which the moisture was. A piece of fruit has moisture in it that keeps the surface moist as well. A piece of steel typically has no moisture in it as it is all solid; in a wind, the peice of fruit will lose more heat than will the piece of steel; however, the difference between the two will typically be to small to notice. It is interesting to note that the chill of the wind actually comes from evaporation of moisture, not from the wind. The wind is actually adding heat to a body through friction, but the evaporation of moisture removes more than the wind adds, at temperatures less than about 60 degrees F. —Preceding unsigned comment added by DWL37 (talk • contribs) 19:15, 16 January 2008 (UTC)

[edit] Frostbite

The tables indicate that the adjusted temperature can be below 0 C even though the actual is over 0 C. Does this mean that an ice cube will not melt in +5 C if there is sufficient wind?

Windchill is a percieved measurement by the body on how cold it is. It is not something that is absolute and can be measured by instruments. Wind Chill is calcualted by pretending humans are a certin shapes etc and seeing how quickly the heat disapates from them in a series of lab experiments, at least from what i can understand.

So you can't use the charts for an Ice Cube as they were designed for humans, and the actual temperature does not change depending on the wind. So i guess no, the ice cube would still melt regardless of the wind. Philbentley 23:30, 15 November 2006 (UTC)

also, as i understand it, the wind chill makes you feel colder by evaporating water off your skin. it heats up the water on your surface and when that water goes away you feel colder. presumably the wind would have a similar effect on an ice cube - i'm not sure how this would effect melting, per se, but in terms of the cube shrinking, it would probably be faster in higher wind. --dan 07:31, 30 November 2006 (UTC)

Frostbite is dependent on several factors including temperature. If the bollod circulation in an area is high the skin is warmed countering the effect of the cold and reducing the incidence of frostbite. Does the wind chill formula assume an inactive subject?Haans42 15:46, 5 February 2007 (UTC)

[edit] Inanimate Objects

It would be useful to mention in the article that wind chill cannot reduce the temperature of an object below the ambient air temperature.(except if there is supercooling due to some evaproative effect) So if the wind chill is -60 and the coolant in your automobile engine coolant/antifreeze is only rated to -40 your engine block will not freeze as the common misconception. Haans42 15:46, 5 February 2007 (UTC)

[edit] Random Question

Can there be wind chill at absolute zero? —The preceding unsigned comment was added by 160.39.169.6 (talk) 17:16, 26 January 2007 (UTC).

That's a clever question; however, as absolute zero is defined as the point where molecular motion ceases (temperature being directly proportional to how much the molecules are moving), there can be no wind-- as wind would require molecular movement, and therefore heat, and therefore a temperature above Zero. See the Absolute Zero article for more info. --BLP 16:16, 4 February 2007 (UTC)
Even cleverer answer. Thank you for the quick response. 160.39.169.89 06:52, 5 February 2007 (UTC)

how can water freeze above 32degs?

Well, the molecular motion cited above refers to thermal agitation. It is correct that this motion stops at absolute zero, however the collective motion of atoms, e.g. translation of a solid (or a liquid if near zero) would be allowed.

However, wind can be defined as the relative motion of a gas with respect to a solid surface. the problem at absolute zero is that no gas would exist, it would condensate to a liquid. In this sense, the above answer may be correct.

But an important detail is that wind chill is related to human feelings. Since no human can survive at the absolute zero, I think that it is quite correct to say that no wind chill may exist at absolute zero :-) Cloren 20:50, 12 September 2007 (UTC)

[edit] Watts per Square Meter wind chill factor

I've added a sentence to the main article mentioning the use of Wind Chill Factor measured in Watts per square Meter that I remember being used in the 1980s. (I lived in Saskatoon Canada, so in January & February we would hear reports on the radio of "the wind chill is 2100 today, so bundle up!" If anyone can expand on it in the article, feel free. / Dzubint 14:06, 5 February 2007 (UTC)

I'm no expert on wind chill, but it seems to me that the article lacks precision. There is absolutely no mention of the fact that wind chill is a perceived temperature change, and not an actual temperature change (as I understand it). The section on 'definitions' does not give any definitions. After reading the article 4 or 5 times, I still don't have a clear picture of what is wind chill... To be fair, there are some very interesting and revealing pieces of information. Maybe lacks an 'encyclopedic' touch. —Preceding unsigned comment added by 72.137.49.53 (talk) 06:28, 5 December 2007 (UTC)

[edit] Also known as Wind Shield?

I've heard several people refer to wind chill as wind shield. Is this just a case of misheard words or is wind shield a proper term? —The preceding unsigned comment was added by 71.48.123.175 (talk) 04:48, 2 April 2007 (UTC).

Misheard words. A windshield (follow the link) is something else. —Lowellian (reply) 01:36, 28 June 2007 (UTC)

ITS A CONSPIRACY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[edit] Graduses

Why big chrart at the top in °F not in world standart °C? 89.208.93.236 18:23, 17 August 2007 (UTC)

[edit] Rewrite

Someone needs to rewire this. Has the person who wrote this ever opened an Encyclopedia? —Preceding unsigned comment added by 128.146.33.195 (talk) 19:55, 14 December 2007 (UTC)

Agreed. Much of this article uses a very unusual writing style for an encyclopedia and reads more like a position paper or essay. Opinions about how things should be are sprinkled in with factual writing. The article also seems to have a self-referencing tone, as though it's patting itself on the back for how well it's written or how smart its explanations are. Very odd. As soon as I get some time during the hectic holidays, I'll start rewriting this myself, but if anyone gets time before I do, please feel free. --DavidGC (talk) 14:59, 23 December 2007 (UTC)