warm and cold winds

[Mike & Martha Savage]

"Warm" winds are simply the motion of air that has become warm (through
contact with the ground, absorption of radiation and especially the latent
heat of condensation). In the Southern Hemisphere warm winds are those that
blow from the north ( from equatorial regions towards polar regions) In the
Northern hemisphere it is the reverse with warm winds emanating from the
south. Similarly "cold" winds are the movement of airmasses that have become
cold through contact with colder surfaces and radiative losses. Southern
hemisphere cold winds blow up from the south.

Winds are excited and sustained by differences in pressure brought about by
differential heating. The Earth's rotation induces a change in direction
such that as air moves from high to low pressure it crosses the isobars at a
shallow angle with a component towards the centre of low pressure.

There is no significant heating of air masses due to their motion. Indeed,
temperature is the kinetic energy of particles, but it is the particles
vibrational motion at the molecular level that is at issue; the large scale
motion of air streams is a different matter.

Cheers

Mike Savage

Samuel Marsden Collegiate School Physics teacher (and long ago the
meteorologist-in-charge at the Amundsen-Scott South Pole Station)

 


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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

 

Can someone help?

 

I got myself in a bit of a confuddle yesterday trying to answer a pupils
question.

 

"Sir, why, if temperature is to do with Kinetic Energy is wind cold?"

 

I started on evaporation from the skin etc and the idea of us 'feeling'
cold, when he asked

 

"Why do we have warm winds? What's the difference?"

 

I started to answer then stopped. What makes air particles travelling at
whatever kph warm or cold?

 

Cheers

 

 

David King

Physics HoD

Christ's College

Private Bag 4900

Christchurch

New Zealand

 





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