The angle of dip of sunrays plays an important role in influencing the quantity of insolation. The direct rays of the sun provide more insolation than the slant rays.
This is because of the following two reasons:
1. The direct rays have to cross the narrower layer of the atmosphere, therefore less energy is destroyed in the atmosphere. While skewed rays cross the broader part of the atmosphere, so more energy is destroyed in the atmosphere.
2. The direct rays heat lesser part of the surface while the same amount of slant rays warm a greater area of the surface. Therefore, direct rays provide more insolation than slant rays.
