warm and cold winds

[David King]

Many thanks to all.

A night's sleep and some clear explanations have helped greatly.

Cheers


David King
Physics HoD
Christ's College
Private Bag 4900
Christchurch
New Zealand




On 9/05/2008, at 8:21 AM, Bryden, Francis wrote:

> Hi David
>
>
>
> The way I think of it is……….
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> The temperature of the air (and the thermal energy your skin loses  
> to it ) depends on the kinetic energy of the randomly moving  
> particles.
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> In warm air the particles have greater KE and so the skin loses  
> less thermal energy because there is a smaller temperature gradient.
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> I suspect the KE of the airparticles due to the wind is small  
> compared with the KE due to their normal random motion.
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> (Wind has no effect on the temperature of a thermometer. Point a  
> fan at a thermometer and the effect is negligible.)
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>  Wind has two effects on us.
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>  We are usually warmer than the air, and there is a layer of warm  
> air near our skin that we have heated up, this will keep us warm.  
> Any wind will move this warm layer away.
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> Because we sweat, wind will also cool us as it increases the rate  
> of evaporation, taking thermal energy from our skin
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> Thanks ................ Francis
>
>
>
> Francis Bryden
>
> HoD Physics
>
> St Cuthbert's College
>
> 122 Market Rd               or Box 26 020
>
> Epsom                              Epsom
>
> Auckland 1051                   Auckland 1344
>
> New Zealand                      New Zealand
>
>
>
> ph: 63 9 5204159 ext 7808
>
>
>
> fbryden at stcuthberts.school.nz
>
>
>
>
> -----Original Message-----
> From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk- 
> bounces at nzip.org.nz] On Behalf Of David Housden
> Sent: Friday, 9 May 2008 6:59 a.m.
> To: phys-teach-talk at nzip.org.nz
> Subject: FW: warm and cold winds
>
>
>
> Hi all
>
> I’m not sure this actually got sent to everyone so I will resend on  
> David King’s behalf.
>
> Cheers
>
> David Housden
>
>
>
>
>
>
> From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk- 
> bounces at nzip.org.nz] On Behalf Of David King
> Sent: Thursday, 8 May 2008 11:01 p.m.
> To: PHYSICS TALK
> Subject: warm and cold winds
>
>
>
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>
>
> Can someone help?
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> I got myself in a bit of a confuddle yesterday trying to answer a  
> pupils question.
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> "Sir, why, if temperature is to do with Kinetic Energy is wind cold?"
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> I started on evaporation from the skin etc and the idea of us  
> 'feeling' cold, when he asked
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> "Why do we have warm winds? What's the difference?"
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> I started to answer then stopped. What makes air particles  
> travelling at whatever kph warm or cold?
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> Cheers
>
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> David King
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> Physics HoD
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> Christ's College
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> Private Bag 4900
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> Christchurch
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> New Zealand
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