Solar Incidence Angle
This work presents changes of the angle at which the Sun's rays strike the Earth's surface during the year. It is aiming to explain what causes the change of seasons.
I calculated the angle of incidence of the sunlight for each day of the year for 50° North latitude (app. Europe). The temperature of the Earth’s surface, and therefore the season, depends on this angle: the larger it is, the more the surface heats up. Changes in this angle are caused by the tilt of the Earth’s axis by 23.5 °.