Azimuth

An azimuth is the angle formed by the line passing by the 2 points and the line of the 2 poles.

The formula to calculate an azimuth is $$ \operatorname{azimuth} = \operatorname{atan2}(y, x) $$ with

\operatorname{atan2}(y,x) = 2 \arctan \frac{y}{\sqrt{x^2+y^2}+x} \), \( x = \cos(lat_1) * \sin(lat_2) - \sin(lat_1)*\cos(lat_2)*\cos(long_2-long_1) \) and \( y = \sin(long_2-long_1)*\cos(lat_2) \)

The angle is calculated by taking as base the north geographic pole.

Every hour, the Earth rotates on itself about 15 degrees, so every hour on Earth, we see the sun 15 degrees further west.

By knowing the azimuth of the sun, we can deduce the time. At noon, the sun is 180 degrees. Each difference of 15 degrees is 1 hour.

Example: The azimuth of the sun at 165 degrees: it is around 11 am.

Example: The azimuth of the sun at 210 degrees: it is about 2 pm.

The given time is Solar Time.

It's the same with an orthographic variant, both spellings are accepted.