NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Anomalous dip. was: [NAV-L] Testing pocket sextant.
From: Alexandre Eremenko
Date: 2006 Jun 16, 10:01 -0400
From: Alexandre Eremenko
Date: 2006 Jun 16, 10:01 -0400
Dear Marcel and George, > I guess you ment -0.0065 ? > > Alex wrote: > "The water was very cool (and always is) here. I mean most people do not > dare to swim in Kiel till the beginning of August:-) But the air was hot, at > least that was what I felt:-)" > > Isn't that just the type of condition to create a high temperature gradient? There is some confusion here. Under the conditions I described, the gradient will be high indeed, but in what direction? The air is cooler nearer the surface. That is the temperature INCREASES with height. If I understood George's message correctly, "inversion" that can lead to positive dip occurs when we have the opposite phenomenon: the temperature DECREASES with height. See his example with the desert where the surface is hot and the air is cool. In the case of Kielerforde we are discussing the water was cool and the air hot. So I would expect refraction in the usual direction, maybe stronger than usual. But the dip will be negative. Alex.
