The "atmosphere" refers to the layer of gasses which surround the earth. This layer of gasses is often referred to as air and is held by the earth’s gravity. The atmosphere is an integral life supporter on earth as it absorbs ultraviolet solar radiation, causes the greenhouse effect, and also adjusts the temperature to suit day and night levels. Air is composed of 78.09% of nitrogen gas which represents a higher percentage, followed by 20.95% of oxygen gas that comes second, thirdly is argon at 0.93%, carbon dioxide taking 0.04%, and the remaining percentage occupied by other gasses.
Atmospheric science is the study of the atmosphere. Below is the breakdown of the layers of the atmosphere.
Above the thermopause is the uppermost layer of the atmosphere known as the exosphere. Exosphere extends to a height of about 700km from the exobase. This layer has a composition of less dense helium, hydrogen, and molecules of nitrogen, oxygen and carbon dioxide. Most satellites that orbit the earth are found in the exosphere.
Just above the mesopause is the second highest layer of the atmosphere known as the thermosphere. Thermopause is the boundary that separates the thermosphere from the exosphere. The thermosphere extends from the mesopause to the thermopause to a height of about 80 km. Temperatures in this layer rise with an increase in height due to the absorption of UV radiation by the ozone layer. The layer has no clouds and no water vapor.
On top of the stratosphere is the mesosphere which is the third layer of atmosphere from the surface of the earth. Mesosphere extends to an altitude of about 50 km from the stratosphere to the mesopause which is the boundary between the mesosphere and the second highest layer the thermosphere. In this layer, the higher you go the cooler it becomes up to the mesopause. At temperatures of about -85°C, it is the coolest place on earth. This is the layer where meteors burn and can only be accessed by the use of rockets.
Just above the troposphere and after the tropopause is the second layer known as the stratosphere. The stratosphere extends to a height of about 12 km from the troposphere and an altitude of about 55 km from the surface of the earth. This is the layer that has the ozone layer containing numerous gasses. In the stratosphere, temperature rises with an increase in altitude because the ozone layer absorbs UV radiation from the sun. The high temperatures help in creating a stable atmospheric pressure. The stratosphere is the highest layer that can be reached by aircraft.
The troposphere is the innermost and the lowest layer of the atmosphere from the earth’s surface. It extends to a height of about 12 km from the surface of the earth. The tropopause is a boundary that separates the troposphere from the stratosphere the second layer of the earth. In this layer, temperature reduces with an increase in altitude.
Almost all the atmospheric water vapor is found in this layer, meaning weather takes place in the troposphere.