Earth is circumvented by a blanket of gasses above its exterior. It is known as the atmosphere. Together with the hydrosphere, and lithosphere, the atmosphere forms the building blocks of planet Earth.
Significance of Atmosphere
- Carbon dioxide present in the atmosphere is life breath for lush green forests and plants. Similarly, oxygen is crucial for the survival of human beings.
- It ensures stable temperature over the surface of the Earth.
- The ozone gas present in the Stratosphere component of the atmosphere saves Earth from harmful UltraViolet radiation.
- It saves the planet Earth from entities like an asteroid. The earth is not in a position to have a direct impact on them due to the presence of an atmosphere.
- The pattern of weather is determined by it and hence controls various facets of life.
Composition of Atmosphere
The primary ingredient of the atmosphere among the whole quantum of gasses is Nitrogen. Nitrogen comprises 78.08 per cent (by volume) of the atmosphere.
The detailed composition of all gasses in the atmosphere is as follows
| CONSTITUENT | FORMULA PERCENTAGE (Volume) |
| 1. Nitrogen | N278.08 |
| 2. Oxygen | O220.95 |
| 3. Argon | Ar 0.93 |
| 4. Carbon dioxide | CO20.036 |
| 5. Neon | Ne 0.002 |
| 6. Helium | He 0.0005 |
- Krypto Kr 0.001
- Xenon Xe 0.00009
- Hydrogen H20.0005
The atmosphere also consists of aerosols I.e. the large number of solid and liquid particles. The quantity of gasses present varies as per height. For example, Oxygen is almost absent at the height of 120 km. Carbon dioxide cannot be traced beyond 90 km from the Earth’s surface.
Description of some important gasses are as follows-
- Oxygen – is essential for the existence of life on Earth. However, it constitutes only about 21%. It is a combustible gas and hence has useful properties.
- Nitrogen- is the most abundant gas in the atmosphere and forms a significant proportion of organic mixtures.
- Carbon dioxide is required by plants for survival and is exerted by humans. It has a great role to play in the maintenance of the heat budget. Of late, the percentage of this gas is increasing in the environment and hence the threat of global warming is on the rise.
- Ozone- The function of Ozone depends on its location. In the stratosphere, it acts as a blanket against harmful UV rays and in the troposphere, it acts as a pollutant and even contributes to smog.
- Water Vapour- plays a significant function in regulating the insulation action. It absorbs both incoming solar radiation and long-wave radiation.
Structure of atmosphere
The chronology of layers in the atmosphere (beginning from the bottom) is as follows
1. Troposphere- The word Tropo means turbulence. It is thus the zone of turbulence. It is in this layer, one can find all weather-related spectacles as around 99% moisture is present in this layer. Jet streams can be witnessed till this layer only. This layer extends up to 8 km at the poles and 18 km at the equator. It is thicker at the equator. The lapse rate is common in this layer I.e. temperature decreases with an increase in height. Tropopause is a lid over the troposphere and is a transition zone to the Stratosphere. It has consistent temperatures.
- Stratosphere- It means an arrangement in strata or layers. The lowest layer is made of Ozone gas. It is located up to 50 km from the Earth’s exterior. Airplanes fly just above tropopause as it has the least turbulence and is cloudless.
- Mesosphere- It extends up to 80 km and is a territory where Meteorites perish. It is the coldest layer as well.
- Thermosphere – The temperature increases with an increase in altitude in this layer. Therefore, one can witness an inverse lapse rate here. It also consists of Ionosphere. 5. Ionosphere- this layer is best known for enabling radio communications. It has electrically charged particles and the gasses are ionized. The phenomena of inverse lapse rate are seen here too.
- Exosphere- It is the topmost layer I.e. farther than the altitude of 400 kilometers. It occurs simultaneously with space.
Hence, this summarizes the overall structure of the atmosphere with all the layers in a sequence.
