What does the picture depict in this diagram

Dear student,

The picture depicts the revolution of the Earth and its effects on seasons and the variations of lengths of days and night.

• The sun is vertically overhead at the equator on two days each year(21 March and 22 September). These days will have equal days and nights.These are called equinoxes.
• The sun is vertically overhead at the Tropic of Cancer on 21st June. The northern Hemisphere will have its longest day and shortest night. This is called Summer solstice.
• The sun is vertically overhead at the Tropic of  Capricorn on 22nd December. The southern Hemisphere will have its longest day and shortest night. This is called Winter solstice.

Regards,