7 importance of earth’s atmosphere

beautiful clouds cloudy dramatic

what is the earth’s atmosphere?

The Atmosphere can be defined as the gaseous envelope surrounding the earth.

The atmosphere can also be defined as a grand body from the earth’s surface to outer space and composed of a number of gases.

The estimated mass of the atmosphere is 5.6 × 1014 metric tonnes. It extends over about 400 km height and meteorological events and effects occur in it. The thickness of the gaseous envelope is equal to 1% of the earth’s mean radius.


The usefulness of the atmosphere:

  • It fulfills the biological oxygen demand (BOD) of animal life. 
  • It supplies the necessary precipitation or moisture.  
  • It protects the biological life on the planet from harmful extraterrestrial radiations like UV, by absorbing it through the ozone.  

  • It maintains the warmth of the planet through its greenhouse effect, avoiding the temperature to fall to two extreme limits.(The earth’s temperature in the absence of an atmosphere would have been +950C (day), and -1450C (Night)  
  • It provides the necessary CO2 which is the basic input required to run the photosynthesis process in plants to build biomass.  
  • It provides the necessary medium for the transport of pollen. Seed spores and insets. Many physical-chemical and hydrological processes responsible for weather and climate occur in the atmosphere only.  

  • The atmosphere is a big reservoir of nitrogen. Some plants and microbes can fix this nitrogen for plant growth e.g., Azolla pinara Azotobacter.

structure of the earth’s atmosphere

the atmosphere is divided into four major layers these are:

the troposphere

the troposphere begins at the surface and extends between 7 kilometres at the poles and 17 kilometres at the equator, with some variation due to weather.

this is the layer where we live and where weather happen

troposphere starts from 0 to 12 kilometre and contains 75 % of gases in the atmosphere

as the height increases, temperature decreases, the troposphere that we live in near the surface of the earth

the troposphere is the lowest layer of the atmosphere

the troposphere contains 99 % of the water vapour in the atmosphere

the boundary between the stratosphere and troposphere is called the tropopause


above the tropopause lies the stratosphere

the stratosphere lies 12 to 50 kilometre above the earth’s surface. in this layer temperature increase with height. this is because the stratosphere houses the ozone layer

the ozone layer is warm because it absorbs ultraviolet rays from the sun.

the majority of the ozone layer (about 97%) found in the atmosphere is concentrated in the stratosphere at an altitude of 15 to 55 kilometre above the earth’s surface

this stratospheric ozone provides an important service to life on the earth as it absorbs harmful ultraviolet radiation

the mesosphere

the mesosphere is the layer above the stratosphere

the mesosphere is 50 to 80 kilometres above the earth’s surface

the temperature decrease with height in this layer just as it does on the troposphere

this layer also contain ratios of nitrogen similar to the troposphere, except the concentration are 1000 times less and there is little water vapour there, so the air is too thin for the weather to occur

most of the meteors burn up in this zone of the atmosphere

the thermoshere

the thermosphere is the uppermost layer of the atmosphere

the thermosphere extends 80 kilometres and beyond

in this layer, the temperature increases with height because it is being directly heated by the sun

the thermosphere extends up to between 320 and 380 kilometres

this is where the international space station orbits

the temperature here can rise to 1500 centigrade degrees.

this layer contains:

  • ionosphere: this is the lower part of the atmosphere. it exptend from about 80 to 550 kilometres
  • exosphere: the upper part of thermosphere. it exptend from 550 kilometre to thousands of kilometres