Question

Explain with the help of a diagram how the tilt of the earth’s axis and the revolution cause

1. seasons.
2. variation in the length of day and night; and
3. changes in the altitude of the midday sun at different times of the year.

Answer 1

1. On account of the different positions of the earth with respect to the sun, in its orbit, various types of seasons are caused. The sun remains vertical on Tropic of Cancer on 21st June and on Tropic of Capricorn on 22nd December and on the equator on 21st March and 23rd September. Besides this, the Arctic and the Antarctic Circles, there is the sunlight for six months from March to September and from September to March respectively. The winter season from December to March, spring season from March to June, summer from June to September, and Autumn from September to December in the Northern Hemisphere and vice-versa in the Southern Hemisphere.
   
2. The length of the day decreases from the equator to the Poles. Apart from this, the polar areas experience six month days and six months nights respectively.
3. The belt of sun’s migration lies between the Tropic of Cancer and Capricorn, consequently, the sun remains overhead in this belt, while beyond this belt the sun never remains vertical at noon and the sun’s track remains slanting with the shorter curved path in other regions.