reflectance derivations

1. reflectance from radiance and solar irradiance

   symbol	description	unit	variable name
   \(\theta_{0}\)	solar zenith angle	\(deg\)	solar_zenith_angle {:}
   \(L\)	radiance	\(W/m2/sr\)	radiance {:}
   \(E\)	solar irradiance	\(W/m2\)	irradiance {:}
   \(R\)	reflectance	\(-\)	reflectance {:}

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

   \[R = \frac{\pi L}{E\cos(\theta_{0})}\]

2. reflectance from wavelength radiance and wavelength solar irradiance

   symbol	description	unit	variable name
   \(\theta_{0}\)	solar zenith angle	\(deg\)	solar_zenith_angle {:}
   \(L(\lambda)\)	radiance	\(W/m2/sr/m\)	wavelength_radiance {:}
   \(E(\lambda)\)	solar irradiance	\(W/m2/m\)	wavelength_irradiance {:}
   \(R\)	reflectance	\(-\)	reflectance {:}

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

   \[R = \frac{\pi L(\lambda)}{E(\lambda)\cos(\theta_{0})}\]