scattering angle derivations

1. scattering angle from sensor and solar angles

   symbol	description	unit	variable name
   \(\theta_{0}\)	solar zenith angle	\(deg\)	solar_zenith_angle {:}
   \(\Theta_{s}\)	scattering angle	\(deg\)	scattering_angle {:}
   \(\theta_{S}\)	sensor zenith angle	\(deg\)	sensor_zenith_angle {:}
   \(\varphi_{r}\)	relative azimuth angle	\(deg\)	relative_azimuth_angle {:}

   The pattern : for the dimensions can represent {time}, or no dimensions at all.

   \[\Theta_{s} = \frac{180}{\pi}\arccos\left(-\cos\left(\frac{\pi}{180}\theta_{0}\right)\cos\left(\frac{\pi}{180}\theta_{S}\right) - \sin\left(\frac{\pi}{180}\theta_{0}\right)\sin\left(\frac{\pi}{180}\theta_{S}\right)\cos\left(\frac{\pi}{180}\varphi_{r}\right)\right)\]