How seasons change ?
The earth’s axis is inclined at an angle of 66.65 to the plane of its orbit. As a result of this, the earth is in different position while revolving around the sun. During the half of the year the northern hemisphere tilts towards the sun resulting in the season of summer in the region. During the second half of the year the southern hemisphere tilts towards the sun, and thus experiences summer and northern hemisphere experience winter.
The revolution causes four season :
Spring : When the sun is overhead the equator.
Summer : When the sun is directly overhead the Tropic of Cancer – The north temperature zone experiences summer.
Autumn : When the sun return to the equator and the north temperature zone experiences the season of autumn.
Winter : The sun is at Tropic of Capricorn and the north temperature zone experiences Winner.
Equinoxes : are days where the days and nights are equal. During these days the sun shines directly over the equator.
21st March is called vernal equinox and 23rd September is called autumnal equinox.
Solstice : The time of year when difference between the length of days and nights is the largest it is referred as Solstice.
On, around 21 June, the North Pole tilts towards the sun and the sun shines directly over the Tropic of Cancer which is called summer solstice. On or around 22 December, the earth is at opposite end of its orbit, as a result, the South pole tilts toward the sun. This results in winter Solstice.
Eclipses : When the light of the sun or the moon is obscured by another body the sun or moon is said to be in eclipse.
Lunar Eclipse : When the earth comes between the moon and the sun, the shadow cast by the earth on the moon result is lunar eclipse. Lunar Eclipse occurs only on a full moon day but not on every full moon day.
Solar Eclipse : When the moon comes between the earth and the sun, it causes obstruction of sun light when viewed from the earth and is called solar eclipse. A solar eclipse A solar eclipse occur on a new moon day and not on every new moon day.
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