Question.
Give reasons, why do amount of insolation decreases from the equator towards the poles?
( Chapter - 4 Air, Class 7 NCERT, Our Environment( Geography) )
Answer.
Insolation means incoming solar radiation, insolation of any region is directly dependent on the duration of sunlight and the angle of incidence of sun rays. The equator region gets maximum insolation as the angle of incidence of around 90 degrees and there is nearly equal day and equal night whereas the polar region receives the lowest insolation on earth as there six month days and six months of night and sun rays are very slanting that not provide much heat as it travel long distance. So it is true, the amount of insolation decreases from the equator towards the poles because-
- Earth is in largely spherical shape.
- earth rotation on its axis at a tilted angle ( 23.5 degrees from the axis).
Due to the spherical shape of the earth and rotation at a tilted angle, the amount of insolation from the equator towards the poles decrease as sunrays become more to more slanting when we go away from the equator to the poles.
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