Effect of Sun angle on climate

Seasonal change in the angle of sunlight, caused by the tilt of Earth's axis, is the basic mechanism that results in warmer weather in summer than in winter.

[2][3] Figure 1 presents a case when sunlight shines on Earth at a lower angle (Sun closer to the horizon), the energy of the sunlight is spread over a larger area, and is therefore weaker than if the Sun is higher overhead and the energy is concentrated on a smaller area.

Therefore, greater tilt means a lower minimum for the same maximum: less total annual surface insolation at the equator.

Therefore, greater tilt means a higher maximum for the same minimum: more total annual surface insolation at the poles.

Although individual mechanisms (such as axial tilt and sun angle) are thought to be understood, the overall impact of orbital forcing on global climate remains poorly constrained.

Figure 1
This diagram illustrates how sunlight is spread over a greater area in the polar regions . In addition to the density of incident light, the dissipation of light in the atmosphere is greater when it falls at a shallow angle.
Figure 2
One sunbeam one mile wide shines on the ground at a 90° angle, and another at a 30° angle. The one at a shallower angle covers twice as much area with the same amount of light energy.
Figure 3
This is a diagram of the seasons. Regardless of the time of day (i.e. Earth 's rotation on its axis), the North Pole will be dark, and the South Pole will be illuminated; see also arctic winter .
Seasonal differences in the Sun's declination , as viewed from the mid-northern city of New York , New York
This solargraph exposed over the course of a year shows the Sun's paths of diurnal motion , as seen from Budapest in 2014.
This graph shows a very simple approximation of relative solar-noon heating on Earth as a function of season and latitude, as resulting from the geometry of the sun elevation angle.