Dear reto ambrosini,
Thank you for the reality check on the sunrise formula. It is not an
approximation but an accurate mathematical formula for an ideal world.
Thank goodness we live in the real world where there is air to breath and a
large sun to keep us warm. For this real world we have to make adjustments.
The fine print in my original note said "ignoring refraction and
semi-diameter, etc". I am glad that you raised the question and others have
answered it so well.
The basic formula for altitude, sin A = sin L * sin D - cos L * cos D * cos
t, is also beautiful in its symmetry but it is too long to fit on a tee
shirt, even here in North America where the most popular size is XL.
Let me keep the thread going with another challenge. You have all observed
how much larger the full moon is when it is near the horizon, rising or
setting, compared to when it is high in the sky. Does this effect also
apply to the sun at sunrise and sunset? Is a larger semi-diameter
correction needed to account for this?
Roger Bailey
Walking Shadow Designs
Canmore, Alberta, Canada
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