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The process by which the Earth orbits around the sun is called revolution, usually Earth revolution. This process takes three hundred and sixty five and a quarter days for a normal year and three hundred and sixty six days for a leap year, to complete one cycle. The Earth's orbit around the Sun is elliptical.
While the process by which the earth rotates along its own axis is called Earth rotation. It takes twenty four hours for the Earth to complete one rotation. Whereas the axial tilt of the Earth is the angle between the Earth's rotational axis and the line perpendicular to its orbital plane. (Wikipedia) The axial tilt is also referred to as the obliquity of the ecliptic.
The effects of revolution, rotation and axial tilt on seasons
The rotation of the Earth around its own axis results into two events, which are day and night. It is evident that at any given time, one half of the Earth faces the Sun, hence daylight. While the other half faces away from the Sun, hence night.
The axial tilt of the Earth causes a given part of the Earth to lean towards the Sun, while the other parts face away from the Sun, as a result different parts of the Earth receives different amount of sunlight and heat.
During the revolution of the Earth, there is a time when the Southern Hemisphere faces the sun while the Northern Hemisphere faces away from the Sun. During this time the Southern Hemisphere receives more sunlight and heat which makes it warmer thus it experiences summer. While the Northern Hemisphere receives lesser sunlight and heat thus experiences winter.
As the Earth revolution continues the axial tilt changes. The relative position of the Earth's axis to the Sun does change during this cycle. This event is responsible for the annual changes in the height of the Sun above the horizon. It also causes the seasons of a year, by controlling the intensity and duration of sunlight received on different parts of the Earth.
The variation of the axial tilt results into two major events, which are the solstice and equinox. The solstices are June and December solstice while the equinoxes are the September and March equinoxes.
During the June solstice the area above the Arctic Circle experiences twenty four hours of daylight, since the North Pole is tilted 23.5 degrees towards the Sun. when the North pole is tilted 23.5 degrees away from the Sun in December solstice, the Arctic circle experiences twenty fours of night. During the two equinoxes, the circle of illumination cuts through the polar axis and the whole Earth experiences twelve hours of day and night.
The temperature of the atmosphere varies with the distance from the equator and the height above the sea level. Temperature also changes in time, which varies from one season to another. For instance when the Northern hemisphere is experiencing summer and the Southern Hemisphere experiencing winter, the atmospheric temperature on the Northern Hemisphere will be higher compared to the Southern Hemisphere.