Layers of Earth’s Atmosphere
The Earth’s atmosphere is divided into five main layers based on temperature variations. These are called as troposphere, stratosphere, mesosphere, thermosphere, and exosphere. These layers are characterized by different temperatures, densities and compositions. Each of the layer of the atmosphere plays a vital role in for pattern of weather and climate. In short the layers of the atmosphere helps to protection of life on Earth.
The structure of atmosphere is an important topic in the World Geography in connection of the syllabus of any of the competitive or academic examination. In this article we are going to discuss the structure of earth’s atmosphere and its different types of layers.
The earth’s atmosphere is composed of many components like wise the structure of the atmosphere is also the combination of various layers.
Structure of the Atmosphere
There are five layers in the structure of the earth’s atmosphere depending upon temperature. These layers are –
01) Troposphere
02) Stratosphere
03) Mesosphere
04) Thermosphere
05) Exosphere
Before we start learn about the Structure of earth’s atmosphere we have to know first what is Atmosphere and what is the role of atmosphere. so tie your seat belts and come with me for a verbal tour of atmosphere.
What is Atmosphere?
Atmosphere is a gaseous cover of the planet, which is known as the earth and the earth is enveloped by a deep blanket of gases extending to several kilometres above their surface. The atmosphere is also an integral part of the earth like Lithosphere and Hydrosphere (Land and Water).
As compared to the radius of the earth’s atmosphere the air and other gases are found in a very thin layer in the earth’s atmosphere and because of the gravitational force of the earth these are inseparable from the earth.
Structure of the Earth’s Atmosphere
The atmosphere of the earth is divided into five different layers to study and understand better. Each of the layer of the earth’s atmosphere having its own peculiar characteristics. The characteristics of the layers are systematically discussed below.
Troposphere
01) Troposphere is the immediate first layer of the earth’s atmosphere.
02) This atmospheric layer lies from the surface of the earth to an average height of about 12 kilometers.
03) There is the difference in the altitude of this atmospheric layer at the poles and the equator of the earth.
04) The altitude of this atmospheric layer is lower at Earth’s poles about 8 kms and higher at the equator about 18 kms
05) The thickness of this atmospheric layer is different on pole and equator.
06) The thickness of this layer is greater at the equator, because the heated air rises to greater heights.
07) The temperature in this layer falls as goes upwards at the rate of 5°C per kilometer.
08) The temperature reaches -45°C at the poles and -80°C over the equator at Tropopause.
09) The fall in temperature is called as ‘lapse rate’ and the troposphere is marked by temperature inversion, turbulence and eddies.
10) Meteorologically this atmospheric layer is the most significant zone in the entire atmosphere because all the weather phenomena confined here like rainfall, fog and hailstorm etc.
11) This zone is also called the convective region, since all convection stops at Tropopause.
12) This atmospheric layer is also known as the theatre for weather as all water vapours and solid particles lie within this and due to that all cyclones, anticyclones, storms and precipitation occur here.
13) This atmospheric zone is influenced by seasons and jet streams.
14) The end of the layer of troposphere is known as the Tropopause.
Tropopause
01) The top most layer of the troposphere.
02) The tropopause acts as the boundary line between troposphere and stratosphere.
03) There is a constant temperatures found at this point of layer.
Stratosphere
01) Stratosphere the second layer of the Earth’s atmosphere lying between the troposphere and the mesosphere.
02) The lower portion of the stratosphere is a layer of constant temperature but the temperatures in its upper levels increase with altitude.
03) The layer of stratosphere starts from the tropopause and extended at about 50 km.
04) The upper most part of the layer of stratosphere is high concentrations of ozone molecules (O3) which creates the ozone layer.
05) The ozone layer absorbed the harmful ultraviolet radiation coming from sun light.
06) This layer of atmosphere is almost free from clouds and weather phenomenon which makes a suitable conditions for flying aeroplanes.
Ozonosphere
01) The spans of stratosphere and lower mesosphere is known as Ozonosphere.
02) The Ozonosphere lies at an altitude between 30 km and 60 km from the earth’s surface.
03) The molecules of ozone (O3) present at the upper part of the layer of Stratosphere which reflects the harmful ultraviolet radiation.
04) The ozonosphere is also known as chemosphere because a lot of chemical activity take place here.
05) The production of ozone in the stratosphere layer of atmosphere is due to the breaking of the chemical bonds within oxygen molecules (O2) by high-energy solar photons.
06) This process chemical reaction is called as photodissociation.
07) The ozone layer plays an important role in the exitance of life on Earth.
08) It was observed since the 1970s about the depletion in the ozone layer by the human activities which cause global decrease in stratospheric ozone layer or substantially altered the ozone layer.
Mesosphere
01) The Mesosphere is an atmospheric layer starts intermediate after the ozone layer.
02) The layer of Mesosphere continues upto an altitude of 80 km from the earth’s surface.
03) The temperature gradually falls to -100°C at the altitude of 80 km.
04) Any meteorites or any external object from the space burned up as soon as they enter in the atmosphere in the presence of layer of Mesosphere in atmosphere.
Thermosphere
01) The thermosphere is the 4th layer of the earth’s atmosphere.
02) This layer is located above the mesosphere and is one of the outermost layers of the atmosphere.
03) The extension of this layer from about 90 km to between 500 and 1,000 km above the Earth’s surface.
04) A great variation found in the temperature in this layer
05) The temperature in this layer rises very rapidly with increasing height due to the absorption of solar radiation and it would feel very cold due to the low density of air.
06) The thermosphere is also home to the International Space Station and other satellites.
07) The Ionosphere is a part of this layer.
08) This layer of the atmosphere helps in radio transmission. The radio waves transmitted from the earth are reflected back to the earth by this layer.
09) Aurora’s are observed in lower parts of this layer.
Ionosphere
01) This layer is located between 80 km and 400 km from the earth surface which is an electrically charged layer.
02) This layer is a very active part of the atmosphere which grows and shrinks depending on the energy it absorbs from the Sun.
03) The characteristic of this layer is the ionization of atoms.
04) The radio waves transmitted from the earth are reflected back to the earth by this layer due to electric charged.
05) The temperature starts increasing with height because of radiation from the sun.
Exosphere
01) The word “Exosphere” is derived from a Greek word, where ‘exo’ means outer or external.
02) The exosphere is the outermost layer of the earth’s atmosphere.
03) This layer is located above the thermosphere.
04) The exosphere extends from approximately 600 kms to 10000 kms above the Earth’s surface
05) This layer is region where the exosphere ends, space begins.
06) This layer gradually merges and fades into the vacuum of space.
07) The density of air in this region is extremely thin because the hydrogen is the most commonly found gas in this region.
08) The region fall between the thermosphere and the exosphere is known as Turbopause.
09) The lowest level of the exosphere is known as Exobase.
09) The boundary of the upper side of exosphere is known as geocorona.
10) The geocorona is visible as the blue light that circles the earth in the image taken by the satellite.
11) Exosphere is the region where many satellites, including the notable International Space Station (ISS) orbits because this region is considered to be the best region to place the satellites.
12) The pressure in the exosphere is created due to the storms of solar winds which compress it.
13) Most of the gas particles travel in curved paths of exosphere without colliding with another molecule or atom and eventually arching back into the lower atmosphere due to the gravitational pull.
Significance of the layers of the atmosphere –
01) Protection from Harmful Radiations – The layers of atmosphere protects the exitance of life on earth by shielding from the harmful radiations incoming from outer space specially ultraviolet (UV) radiation.
02) Help in keeping the planet warm – The layers of the atmosphere help in keeping earth warm through insulation and preventing extremes between day and night temperatures.
03) Help to creates weather and climate – The atmosphere play a crucial role in determining weather and climate patterns including temperature, precipitation and wind.
04) Help to maintain ecosystem – These patterns of climate and weather have a significant impact on ecosystems, agriculture, and human activities.
05) The atmosphere plays a major role to maintain the water cycle – The atmosphere helps regulate the Earth’s water cycle by transporting water vapor from the oceans to the land, where it falls as precipitation.
Related Notes
Atmosphere of Earth – A Blanket of Gases
Composition of the Earth’s Atmosphere – UPSC | SSC
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