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Re: Extremely poor conditions??
From: Alexandre Eremenko
Date: 2012 Mar 21, 14:43 -0400
From: Alexandre Eremenko
Date: 2012 Mar 21, 14:43 -0400
David, What I read suggests that the rays near horizon can be indeed bent in any direction, towards Earth or away. The question HOW MUCH can they be bent. Nothing that I read so far suggests that they can be bent THAT MUCH as we observed. Alex. On Wed, 21 Mar 2012, David Fleming wrote: > > Yes, I agree as my prior statement retracted the statement about equality. > > Still terrestrial refraction results in rays with a center of curvature > toward the earth. > > Additionally the increase in air density due to cooling effect of the water > will increase that curvature further raising the apparent position of the > horizon giving the results obtained in your meazsurements > > On Wed, Mar 21, 2012 at 1:24 PM, Alexandre E Eremenko < > eremenko---purdue.edu> wrote: > >> >> David, >> >> >> That is the sun LL is seen 30 min higher in sky than it is. >>> >> >> This means that usual conditions also raise the apparent horizon by the >>> same 30 mins or the visible horizon is further than the geometric horizon. >>> >> >> No. The first statement does not imply the second. Just look at the >> Almanac table for the dip. >> The reason is that the ray from the Sun travels through the whole >> atmosphere (so it has plenty of time to get distorted by 30') >> But the ray from the horizon travels to our eye only few miles. >> So this second ray is distorted much less. >> >> As the dip table in the Almanac shows. >> >> Alex. >> >> >> >> >> >> > > > > > : http://fer3.com/arc/m2.aspx?i=118450 > > >