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Re: Refraction. was: Bubble Horizon Altitude Corrections
From: Trevor Kenchington
Date: 2004 Jul 6, 23:31 +0000
From: Trevor Kenchington
Date: 2004 Jul 6, 23:31 +0000
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@iStar.ca 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