Dewsquad

Hi! I'm new to this forum and signed up to ask a few questions from my course. 1. Lambert's Cosine Law says that radiative flux over an infinitely small area is largest at the perpendicular normal angle. But when the same flux is at an angle, the flux is spread over a larger area and is then proportionally smaller. This can be described with the equation E [perpendicular] = E [perpendicular] * cos(zenith angle) Is this correct? Have I described it right? 2. I have read about Lambertian surfaces, or perfectly diffuse surfaces. Is Lambert's Cosine Law assuming the target of the irradiance is a perfectly diffuse surface? Or is it assuming that the source of the radiation is a perfectly diffuse surface? 3. Lambertian surfaces also talk about perfectly diffuse vs perfect radiator. What is the difference between these two? 4. Is a Lambertian surface assumed to have zero transmission or absorption? Does perfectly diffuse only describe reflection?