Latitudinal effects
Intensity of insolation is not the same at all latitudes
Earth is roughly spherical, so insolation passing through 1 m2 screen
- Illuminates an area = 1 m2 where surface is perpendicular to radiation (near equator)
- Illuminates an area = 1 m2 x (1/sin45°) = ~ 1.4 m2 where surface is inclined ~45° to radiation (at 45° latitude)
- Illuminates an area = 1 m2 x (1/sin30°) = ~ 2 m2 where Earth’s surface is inclined ~30° to radiation (at 60° latitude),
Moving from the equator to the poles, insolation per unit area decreases uniformly