Tag: how seasons occur - part i

After 22nd March, other parallels between the equator and the Tropic of Cancer in the northern hemisphere start receiving perpendicular rays sequentially. Only on 21st June and 22nd December the sunrays become perpendicular on the Tropic of Cancer and Tropic of Capricorn respectively.These two days are called Solstice days.

Sunrays are never perpendicular to any of the parallels between Tropic of Cancer and the North Pole or between Tropic of Capricorn and the South Pole. 22nd December marks the longest day and the shortest night in the southern hemisphere.

The movement of the sun towards the north or south in a year is called the apparent movement of the sun. The revolution of the earth around the sun and the tilted axis of the earth are the two factors responsible for the apparent movement of the sun. Seasons occur only with reference to the northern and the southern hemispheres.

In the northern hemisphere , 21st March is called spring or vernal equinox whereas 23rd September is called autumnal equinox. The equinox or solstice dates can vary by a day or so.