Explanation:

The factors that cause these variations in insolation are :

(i) the rotation of earth on its axis;

(ii) the angle of inclination of the sun’s rays;

(iii) the length of the day;

(iv) the transparency of the atmosphere;

(v) the configuration of land in terms of its aspect.

(The last two however, have less influence).

The fact that the earth’s axis makes an angle of 66½ with the plane of its orbit round the sun has a greater influence on the amount of insolation received at different latitudes.