Tile of the earth axis and the earths orbital rotation
Explanation:
The angle of the inclination of the suns rays are inclined at the 23.5 ° as the earth is itself titled to the angle of the 23.5 degrees and thus due to the anticlockwise rotation of the planet around the sun the earth gets inclined rays that are directed at the earth equator or center and are slanting at the poles and thus perpendicular rays occur at the tropics.
