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  #1  
Old 07-09-2007, 02:13 PM
StarvingButStrong StarvingButStrong is offline
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Does using a hand fan make you cooler or not?

My Grade School days were long before the idea of air conditioning schools occurred to anyone, meaning there were days we were trapped in sweltering classrooms during early June heat waves. Naturally some of us would start fanning ourselves with notebooks or folded paper fans...and invariably the teacher would order us to stop. This fiat was justified by saying the exertion of fanning ourselves created more heat than would be lost to the breeze we created.

Back then, teachers were still regarded as infallible Fonts of Wisdom (silly, I know, but this was before the world had been exposed to the Glory of the Straight Dope) so we accepted this.

Now, however, suffering in a heat wave, I wonder. People have fanned themselves for centuries; if this were truly an ineffectual method of cooling oneself, wouldn't some Archimedes have cried Eureka! and put the fan makers out of business before the pyramids were finished?

I do understand the basics of both procedures. Waving a fan requires muscular exertion, and muscular exertion produces heat as a waste product.

On the other hand, heat makes people sweat. If the air around you is dry enough this sweat evaporates, cooling your skin in the process. Fans create a breeze, causing the probably-nearly-saturated air immediately around your skin to be replaced by fresh, somewhat drier air, allowing the evaporation of sweat to continue, and possibly even speed up.

What I don't know is the qualitative result. *Does* the added heat from the exertion always swamp the increased cooling?

Or were our teachers just miserable SOBs who enjoyed watching us sweat?
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  #2  
Old 07-09-2007, 04:29 PM
missbunny missbunny is offline
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By the time I get into my office in the morning I am usually very warm (I've either walked a mile or nearly that on the un-AC/d train. I always use a manila folder to fan myself and the feeling of being cooler happens nearly immediately. If I fan the back of my neck it's even faster. Maybe I'm not actually cooler, but I feel cooler.

Um how much "exertion" did your teacher think was being created by your wrist moving a couple of inches in either direction? Sounds like an idiotic thing to say.
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Old 07-09-2007, 04:46 PM
Yag Rannavach Yag Rannavach is offline
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Plus, if you're worried about feeling colder instead of actually being colder, then it doesn't really matter whether or not you increase heat in your wrist/arm if you're decreasing it in your face. cite
I'm making an assumption here that probably isn't warranted from that cite specifically, but I think the general idea holds. Namely, that your face is more heat-sensitive than your wrist/arm, or at least has a larger heat-sensitive area.

Last edited by Yag Rannavach; 07-09-2007 at 04:47 PM..
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  #4  
Old 07-09-2007, 05:09 PM
CynicalGabe CynicalGabe is offline
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Not as much as smoking. It requires a certain ensemble to pull off a cooler look with a hand fan. A preppy sweater draped over the shoulders usually works.
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  #5  
Old 07-09-2007, 05:10 PM
teela brown teela brown is online now
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My grade-school teachers said exactly the same thing. As far as I'm concerned, if you feel cooler, you are cooler. I think they just wanted to stop the annoying fluttering of papers.
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  #6  
Old 07-09-2007, 05:13 PM
Tranquilis Tranquilis is offline
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Search the Archives. Relevent Staff Report.

Short answer: Maybe.
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  #7  
Old 07-10-2007, 01:51 AM
Skeptic42 Skeptic42 is offline
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Note that even if I'm cooler if I fan myself than if I don't, all of us in the room may be hotter if we all fan ourselves than if none of us do.
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Old 07-10-2007, 02:11 AM
if6was9 if6was9 is offline
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Quote:
Originally Posted by teela brown
My grade-school teachers said exactly the same thing. As far as I'm concerned, if you feel cooler, you are cooler. I think they just wanted to stop the annoying fluttering of papers.
When we grew up and went to school
There were certain teachers
Who would hurt the children any way they could.
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  #9  
Old 07-10-2007, 03:50 AM
Mangetout Mangetout is offline
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Quote:
Originally Posted by StarvingButStrong
What I don't know is the qualitative result. *Does* the added heat from the exertion always swamp the increased cooling?
There's no reason why it must - although the laws of thermodynamics never go away, this isn't one of those situations of diminishing returns where you can only ever waste effort.
The process by which the fan cools you is sufficiently unrelated to the process by which your body produces heat, that it can't be inevitable that you'll always make yourself hotter.
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  #10  
Old 07-10-2007, 10:53 AM
StarvingButStrong StarvingButStrong is offline
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Looks like we're all agreed, then: the teachers just wanted to watch us sweat miserably.
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  #11  
Old 07-10-2007, 11:00 AM
WhyNot WhyNot is offline
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Okay, now that the GQ has been answered...

As already alluded to, there's a difference between feeling cooler and being cooler. Peppermint essential oil rubbed on your wrists and the back of your neck is an old Ren Faire trick for staying cool-feeling in those heavy outfits, but I doubt that peppermint actually lowers the body's core temperature. Who cares, really? As long as you're feeling cooler (and not nearing heatstroke), that's all that we're really trying to achieve, right?

But, having taught classes in the heat before, I do understand where the teacher was coming from. It's actually really hard to concentrate when people are waving things in your field of vision. Not to mention that children are notoriously incapable of holding onto the items they're waving. She was probably trying to prevent the whine fest that might ensue when Billy flung his folder at Laura and defended himself by saying he was just fanning himself.
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  #12  
Old 07-10-2007, 11:27 AM
Zyada Zyada is offline
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I have a couple of addendums to the staff report.

First, IMHO the assumption can be made that the fanning motion is on the low end of the heat production scale. I couldn't find a cite, but this is the same motion that English royalty use to wave when they are in a three hour parade. I have heard that they use this motion because it take less effort.

Secondly, the heat generated by the motion is in the arm, where it can be easily radiated by the surface area of the arms and hands. Thus the heat produced will be reduced before it can reach the chest cavity and increase core temperature.

Finally, our perception of being hot or cold is governed by the temperature of the blood that is flowing into our head. This is good, because the brain is more sensitive to high temperatures than the rest of the body. Fanning the face, neck and back of neck will reduce the temperature of blood flowing to, and already in the brain.

So, fanning yourself may produce some heat, but is reduced before it gets to your brain, and the fanning directly cools the head, where you really need it.
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