relative azimuth angle derivations
relative azimuth angle from sensor and solar azimuth angle
symbol description unit variable name \(\varphi_{0}\) solar azimuth angle \(deg\) solar_azimuth_angle {:} \(\varphi_{r}\) relative azimuth angle \(deg\) relative_azimuth_angle {:} \(\varphi_{S}\) sensor azimuth angle \(deg\) sensor_azimuth_angle {:} The pattern : for the dimensions can represent {time}, or no dimensions at all.
\begin{eqnarray} \Delta\varphi & = & \varphi_{0} - \varphi_{S} \\ \Delta\varphi & = & \begin{cases} \Delta\varphi \geq 360, & \Delta\varphi - 360 \\ 0 \leq \Delta\varphi < 360, & \Delta\varphi \\ \Delta\varphi < 0, & \Delta\varphi + 360 \end{cases} \\ \varphi_{r} & = & \left|\Delta\varphi - 180 \right| \end{eqnarray}