How does the spherical shape of the earth affect the amount of sunlight that reaches different regions?

Question

1401 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-07-04T02:43:14

The amount is a function of time, latitude and obliquity. Over a the period one year, the angle of incidence of light rays changes periodically..

At latitude #theta^o N#, the angle of incidence of light rays varies

from

#theta# at vernal equinox ( about March 21) through

#theta - 23.4^o# at summer solstice (about June 21 ) through

#theta# again at autumnal equinox ( about September 22) through

#theta+23.4^o# at winter solstice (about December 21) and back to

#theta# at vernal equinox ( about next March 21 ).

For southern latitudes, it is opposite (+ becomes - and - becomes + ).

A careful study of these data would clear all doubts on the variation

of the altitude of the Sun any day and, relatively, the amount of light

received on that day. amount of. light received at any place.

Note that, when the angle of incidence of solar rays is# theta +

23.4^o, for #theta> 66,6^o#, there is no direct sunlight, If at all there

is , it will be reflected sunlight from moon or twilight. .