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From: Trevor J. Kenchington (no email)
Date: Tue Jul 06 2004 - 19:31:37 EDT
I always hesitate to find fault with George's postings because it
usually turns out that the error is mine. However, when he writes:
> If there was a temperature
> gradient in the air, the temperature falling fast enough as height
> increased, that could in theory be enough to counteract the effects of the
> falling pressure. In that case the air-density would conceivably increase,
> not decrease, as height increased, which could cause light to be curved
> upwards, not downwards; the effect that I think Fred is looking for.
I have to ask: George, if the density of the air increased with
altitude, what would stop the dense air from descending and displacing
the lower-density air upwards?
Sure, air masses can be unstable and we do see down draughts and rapidly
rising air (as in cumulus clouds). But can enough high-density air
really sit on top of low-density air for the usual direction of
refraction to be reversed?
Trevor Kenchington
--
Trevor J. Kenchington PhD
Gadus Associates, Office(902) 889-9250
R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251
Nova Scotia B0J 2L0, CANADA Home (902) 889-3555
Science Serving the Fisheries
http://home.istar.ca/~gadus
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