Next message: Frank Reed: "Re: The Online Nautical Almanac- beware!"
Temperature inversion in the San Fernando Valley, California.
Bob
>From: "Trevor J. Kenchington" <>
>Reply-To: Navigation Mailing List <>
>To:
>Subject: Re: Refraction. was: Bubble Horizon Altitude Corrections
>Date: Tue, 6 Jul 2004 23:31:37 +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 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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