How do the latitude and the tilt in the axis of rotation of the earth affect the amount of radiation received at the earth's surface?
The latitude of a place significantly affects the amount of radiation received at the earth's surface. The angle of inclination of the sun's rays depends on the latitude. At higher latitudes, the sun's rays make a smaller angle with the surface, resulting in slant rays. These slant rays cover a larger area compared to vertical rays. When more area is covered, the energy gets distributed over a wider region, and the net energy received per unit area decreases.
Additionally, slant rays have to pass through a greater depth of the atmosphere at higher latitudes. This results in more absorption, scattering, and diffusion of solar radiation before it reaches the surface, further reducing the amount of insolation received.
The tilt in the axis of rotation of the earth also has a greater influence on the amount of insolation received at different latitudes. The earth's axis makes an angle of 66½° with the plane of its orbit around the sun. This tilt causes variations in insolation across latitudes.
Due to these factors, there is a surplus of net radiation balance between 40 degrees north and south, while the regions near the poles have a deficit. The insolation received varies from about 320 Watt/m² in the tropics to about 70 Watt/m² in the poles.
Explanation
This answer addresses both parts of the question—latitude and axial tilt—using only the provided textbook context. The latitude effect is explained through the angle of sun's rays, area coverage, and atmospheric depth. The tilt effect is explained through the 66½° angle with the orbital plane. The answer also includes quantitative data (320 Watt/m² to 70 Watt/m²) and the concept of surplus/deficit radiation zones from the context.