Composition of the Atmosphere

Earth, the blue ball in space is the only planet that supports life. There are many unicellular and multicellular organisms on Earth. They are all supported by the protective layers of the Earth's atmosphere. But have you ever wondered what is the composition of the atmosphere of the Earth? In this article we will learn all about it.

What is Atmosphere?

We all take one of the most important aspects of being called living very lightly. We breath in air, we breath out air, without air we would all suffocate and die. This air is one of the basic things that makes life on Earth a reality. Air is a synonym for atmosphere. But the composition of the atmosphere is more than air. It consists of various gases and other particles. The atmosphere is made up of three primary gases and other trace gases. Particles like dust, water molecules and even pollen make up the atmosphere.

The Earth's atmosphere extends about 6,000 miles above the sky. The first 16 miles is where the bulk of this atmosphere lies. The sky is the first level of the atmosphere that we can see. Above the 16 miles, the atmosphere becomes thinner and thinner and there is less pressure exerted on the matter. Higher the atmosphere, the lighter the body becomes. These various pressures of the atmosphere at different levels causes different effects on the weather, animals and people.

Composition of the Atmosphere

The composition of the atmosphere can be divided into two layers, the heterosphere and the homosphere. The heterosphere is the outermost sphere of the atmosphere where the gases are distributed on distinct layers according to their atomic weight and gravitational pull. The lightest elements that make up the outer layer of the atmosphere are hydrogen and helium. The heavier elements at the base of the outer layer are nitrogen and oxygen.

The layer that lies between the Earth surface and heterosphere is the homosphere. The gases in this layer are uniformly mixed. The ozone layer that extends from 12 to 31 miles lies in this layer. The ozone layer is a very important layer as it helps protect life on the Earth from the harmful effects of the sun's ultraviolet rays.

The three major gases that make up the atmosphere are called constant gases. These constant gases are nitrogen, oxygen and argon. Nitrogen in the atmosphere makes up about 78% of the total composition of the atmosphere. It is one of the building block of life as it is the major component of protein. Oxygen makes up about 21% and is absolutely necessary for plant and animal respiration. Without oxygen fire cannot burn and plants release free oxygen in the atmosphere by photosynthesis. Argon makes only 0.934% of the atmosphere and is a colorless, odorless inert gas.

The other trace gases that make up the atmosphere are called variable gases. These variable gases include methane, hydrogen, helium, neon, krypton, carbon dioxide, and a form of oxygen known as ozone. The following is a list of gases with their percent volume that makes up the atmosphere.

Table of Composition of Atmosphere

Composition of Atmosphere	Chemical Formula	Percent Volume
Nitrogen	N2	78.08%
Oxygen	O2	20.95%
Water (variable gas)	H2	0 to 4%
Argon	Ar	0.934%
Carbon dioxide (variable gas)	CO2	0.0360%
Neon	Ne	0.0018%
Helium	He	0.0005%
Methane (variable gas)	CH4	0.00017%
Hydrogen	H2	0.00005%
Nitrous Oxide (variable gas)	N2O	0.00003%
Ozone (variable gas)	O3	0.00004%

The atmosphere is the reason that we have so many seasons and weather conditions. The atmosphere forms a thick blanket around the Earth that helps protect those on the surface from harmful sunrays, cosmic radiations and heat.