Gravity is the force of the Earth attracts every object towards itself. From our perspective this force always acts downwards. For a long time people did not believe that the Earth is round because then the people 'underneath' the sphere would have actually fallen down. In 1687, a physicist, Isaac Newton, proved that the force of gravity always acts towards the center of the Earth. On the Earth, the force of gravitation always acts downwards irrespective of Eskimos in the Arctic region, people in Europe or inhabitants of Australia.
There is a direct relationship between gravitational acceleration and the downwards weight force experienced by objects on Earth, given by the equation F = ma (force = mass × acceleration). However, other factors such as the rotation of the Earth also contribute to the net acceleration.
The word ‘atmosphere’ means a gaseous cover enveloping a planet. Without atmosphere life would not have been possible on the Earth: One-fifth of the atmosphere is oxygen and four-fifths is nitrogen. Like the Earth’s interior, the atmosphere too is made up of several layers. All animals and plants live in the lowermost layer of the atmosphere called the’ troposphere; All weather phenomena take place in the troposphere. Even Aeroplanes fly in the outer edge of the troposphere. The stratosphere, the mesosphere, the ionosphere, and the exosphere lie above the troposphere.
