Refraction affects apparent altitude at a particular time. The apparent
azimuth at a particular time does not change.
But the time of sunrise/sunset is changed due to refraction, so
therefore there is a different solar azimuth at this adjusted time.
On 2013-11-13 11:28, Frank King wrote:
Dear David,
You say, in the context of calculating solar
azimuth that...
Refraction has no effect on azimuth...
Hmmm. This is absolutely true but, alas, the
truth may well throw a beginner.
Imagine calculating the azimuth of sunrise
and going out with a friend one morning
before dawn and pointing confidently
where the sun will rise.
Unless your calculation takes account of
refraction you will have the time of
sunrise wrong and hence the azimuth.
Refraction means that the sun appears
to rise before naive calculation says
it will and, hence, its azimuth will
be displaced.
One of the great things about sundials
is that even the simplest problem gets
tougher once you look at it carefully!
Frank King
Cambridge, U.K.
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