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Composition and Structure of the Atmosphere

The atmosphere is a combination of various gases that sheathes the earth. The air is an essential part of the earth’s mass, and 99%of it is constricted to the peak of 32 km from the earth’s surface.

Composition Of Atmosphere: 

  1. The atmosphere has water vapor, gases (nitrogen, oxygen, etc.), and dust particles.
  2. The gas’s proportion changes in the higher layers of the atmosphere. The proportion changes so that at the height of 120 km, oxygen will be almost in negligible quantity. 
  3. Water vapor and carbon dioxide are found only up to 90 km from the earth’s surface.

Gases: 

Carbon dioxide: is an essential gas as it is opaque to the outgoing longwave radiation but transparent to the incoming solar power. It soaks in a part of electromagnetic radiation and mirrors back some of it. It is responsible for the greenhouse effect. Co2 has been on the rise for the past few decades because of fossil fuel burning, and it has increased the temperature of the gasses.

Ozone: It is found between 10 and 50 km above the earth’s surface and acts as a filter and absorbs the ultraviolet rays radiating from the sun and prevents them from reaching the surface of the earth.

Nitrogen: Nitrogen is the most prevalent element in the Earth’s atmosphere, accounting for roughly 78 percent of the total! All living things, including humans, require nitrogen. Plants cannot survive if there is insufficient nitrogen, resulting in inadequate agricultural yields; yet, too much nitrogen can be hazardous to plants. While nitrogen is required for our food supply, too much nitrogen can be harmful to the ecosystem.

Oxygen: The quantity of molecular oxygen, O2, in the atmosphere, particularly in the troposphere, that permits life to flourish is referred to as oxygen. Humans’ most basic requirement is atmospheric oxygen, which is even more crucial than food.

Water Vapour: 

  • Water vapor is also a wavering gas. It diminishes with height
  • In the warm and wet tropics, it may account for 4% of the air by volume, while it may be less than 1% of the air in the dry and cold areas
  • The volume of water vapor decreases from the equator towards the poles

Dust Particle:  

  • The atmosphere has a sufficient capacity to keep small solid particles that may originate from different sources, including sea salts, smoke-soot, ash, fine soil, dust, and disintegrated particles of meteors and pollen
  • Dust particles are usually present in the lower layers of the atmosphere, air currents may bring them to greater heights

Structure of the Atmosphere:

  • The atmosphere consists of various layers with varying densities and temperatures
  • The density decreases with increasing altitude and is high when close to the earth’s surface
  • The atmosphere’s column is divided into five layers based on the temperature

Troposphere:

  • The troposphere is the lowest layer of the atmosphere
  • The Troposphere has an average height of 13 km. It extends to 8 km at the poles and about 18 km near the equator
  • The thickness of the troposphere is high at the equator because heat is brought to great heights by sturdy convection currents
  • The troposphere layer contains water vapor and dust particles., the temperature in this layer decreases at 1°C for every 165m of height 
  • This is an essential layer for all biological activity                                                                                                                                            The Tropopause is the zone that separates the stratosphere from the troposphere. The temperature at the tropopause is about -80oC over the equator and about -45oC over the poles. It is called tropopause, as the temperature in tropopause is nearly constant.

Stratosphere:

  • It is found on top of the tropopause and expands up to 50 km 
  • It has the ozone layer that takes the ultraviolet radiation and protects life from intense, harmful forms of energy, temperatures are at an average of −51 °C

Mesosphere:

  • It is on top of the stratosphere, extending up to 80 km
  • In this layer, the temperature diminishes with the increase in height and goes up to -100°C at the height of 80 km
  • Mesopause: It is the upper limit of the mesosphere

Ionosphere:

  • The Ionosphere is above the mesopause
  • It comprises ions, which are electrically charged particles
  • With its assistance, radio waves transmitted from the earth are reflected
  • In this layer, the temperature starts increasing with altitude

Exosphere:

  • The exosphere is the uppermost layer of the atmosphere above the thermosphere
  • It is the highest layer, and very little is known about it
  • In this layer, the contents are extraordinarily lofty, and it gradually merges with the outer space

Conclusion

It is important to study the composition and structure of the Atmosphere.

It provides air for the living creatures to breathe and acts as a blanket protecting life on earth from harmful solar radiation. The various layers of the atmosphere are arranged to carry out a wide range of functions.