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At 18:55 06/09/2006, you wrote:
>Imagine that you've parked your car outside on a hot summer day.  When you
>open the doors after a couple of hours, you're blasted with the heat that
>has built up inside.  Is this "new heat"?  If so, could this (gazillions
>of cars sitting around) theoretically contribute to an excess of global
>heat (global warming)?
:
>My new friend is looking for equations and the like to prove the point -
>one way or the other

I'm no physicist, but reckon that figuring out a simple way to avoid 
confusion is a science in itself. Here's my contribution...

Heat 'shining' onto the car = heat reflected and re-radiated by the 
car + heat lost by convection-warming the air outside the car + heat 
temporarily stored in the hot car, some of which escapes with the hot 
air when the door is opened, with the rest also being lost by 
radiation and convection after sunset.

Everything balances. Heat isn't being gained from 'nowhere'.

If the car had not been there, a similar equation could have been 
applied to the heat 'shining' onto the ground. The ground is likely 
to store (again, temporarily) even more heat than the car, but has no 
door to open, letting out that spectacular rush of warm air which 
confused your friend.


[log in to unmask] * http://www.interactives.co.uk
*
Give people facts and you feed their minds for an hour.
Awaken curiosity and they feed their own minds for a lifetime.
*
Ian Russell 

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