Atmosphere:

Atmosphere is a layer of gases that surrounds the Earth and is held together by the Earth’s gravity. It consists of roughly 78% nitrogen and 21% oxygen, with water vapor , carbon dioxide and other gases .It is 8Km thick ,with variations through out the surface of Earth.

Besides the air we breathe, atmosphere provides a greenhouse effect, blocking out the harmful elements of the Sun’s rays which is ultraviolet solar radiation.

Atmosphere also transports water vapor causing rain and moderates the Earth’s temperature. The heating and reheating of air causes shifting of hot and cool air called atmospheric circulation. This circulation is what causes shift in weather and climate.

Without atmosphere’s effect of green housing and temperature control, the Earth would be -18⁰C making the life impossible.

Season:

Changing seasons are caused by the Earth’s movement. The Earth completes a rotation on its axis in a day and takes a year to complete a revolution of the sun.

These two movements create variation in temperature, weather and seasons. The distance of the Sun is 146 million Km from the Earth and the Earth temperature varies between -89⁰C to 57.7⁰C.

During the rotation the part of the Earth’ surface facing the Sun, experiencing midday while the other side of the Earth ha a cool night.

The Earth is inclined at an angle of 66.5⁰.

During the first half of the year, the Northern hemisphere is closer to the Sun, and experiences summer, while the Southern hemisphere experiences winter. In the second half, the axis of the Earth tilts the other way and the Southern hemisphere faces the Sun, thus experiencing summer.