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Thu, 7 Sep 2006 13:31:26 +0100 |
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ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
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At 12:23 07/09/2006, I wrote:
>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.
Come to think of it, the same area of bare ground is likely store
less heat than the car. Hot ground and hot car-seats both radiate
some heat back towards the sky, but the longer wavelength of this
radiation is less able to pass outwards through the car window-glass.
The energy equation has to balance, so more heat builds up inside the car.
Comparing a parked car with a similarly sized patch of ground seems a
useful way to consider this 'greenhouse effect'. The difference
between the car and our planet being that a planet can ONLY lose heat
through its atmospheric window, so it isn't likely to cool down as
much as the car at night...
[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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