The atmosphere can be defined as a layer of gases that surrounds the planet earth or any other celestial body with a sufficient mass to be considered a celestial body in its own right. The atmosphere stretches up to 1000 km above the surface of the globe. However, because of the great gravitational attraction of the planet, it is possible to feel practically the whole mass of the atmosphere within 32 km of its surface. This layer of the atmosphere is composed of a variety of gases in varying proportions, such as nitrogen at 78 percent and oxygen at 21 percent; the remaining 1% is made up of gases such as argon, carbon dioxide, neon, and helium, among others.
It acts as a protective barrier between outer space and the biosphere, protecting both from harm. It is a mixture of gases that is odourless, colourless, tasteless, and formless that has been extensively mixed and blended to the point where it behaves as if it were a single gas.
The gases that make up the current atmosphere are not a direct byproduct of the early stages of the earth’s development, as previously thought. In the course of evolution, volcanic eruptions, hot springs, chemical breakdowns of solid materials, and redistribution from the biosphere have all contributed to their formation.
As a result of its presence, the earth is shielded from dangerous solar radiation. A greenhouse effect is achieved by allowing short-wave radiation (from the Sun) to pass through while trapping long-wave terrestrial radiation (from the Earth’s surface).
All living things require a specified range of temperatures as well as a specific range of solar radiation frequencies in order to carry out their biophysical processes properly. Certain frequencies of solar radiation are absorbed by the atmosphere, whereas other frequencies are allowed to pass through. In other words, the atmosphere regulates the amount of solar radiation that enters the Earth’s atmosphere.
The spread of the Atmosphere bends till 1000 kilometres above the globe’s surface. However, its mass can be felt within 32 kilometres of the surface area of the globe- because of the strong gravitational pull of the planet. The atmospheric layer is made of several gases-
- 78 percent of the gases consist of Nitrogen
- 21 percent of the gases consist of Oxygen gas
- 1 percent of the gas includes several- neon, helium, carbon dioxide, etc.
Air is known to be the mixture of gases; while the Atmosphere is known as the blend of gases. This blend of gases can be divided into five layers- which we often recognize as the different layers of atmosphere. Each of these layers of atmosphere has the responsibility of protecting life and living conditions on Earth. The density and distribution of gases in each of these layers of atmosphere are distinct from one another. These layers are the result of years of evolution, chemical breakdowns, hot springs, volcanic eruptions, and other natural forces- which all contributed to the formation of the different layers of atmosphere.
Different layers of Atmosphere
As mentioned above, the blend of gases that blankets the Planet Earth can be divided into five layers- which we often recognize as the different layers of atmosphere. The mixture of the gases is odourless, tasteless, colourless, and formless. These layers of atmosphere are- Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. All these layers have distinct temperatures- and are layered based on these temperature differences. In addition, the solidity and the dispensation of these layers of atmosphere are also different. These layers help in making the living conditions on Earth alive and the protection of these conditions is a vital responsibility of these layers. These layers play a role in protecting Earth from the ultra-violent and harmful of the Sun.
Now, let us look at the different layers of atmosphere in detail.
- Thermosphere (Ionosphere)
- It is the layer of the atmosphere that is closest to the ground. It can be as long as 18 km in the equator, 13 km at mid-latitude, and approximately 8 kilometres at the poles.
- It makes up around 90 percent of the total mass of the atmosphere, according to NASA.
- This layer is responsible for the entirety of the weather phenomenon. It is made up of all of the water vapour, dust particles, clouds, and so on.
- The temperature in the troposphere falls as the altitude of the atmosphere rises.
- It is located above the troposphere and spreads consistently around the globe up to a distance of 50 kilometres.
- The presence of the Ozonosphere distinguishes this layer from the others. Ozone is a highly reactive oxygen molecule composed of three atoms that is highly reactive in nature.
- The high-frequency UV radiation is absorbed by the ozone layer. As a result of this absorption, the temperature of the layer rises significantly.
- The mesosphere is located between 50 and 80 kilometres above the surface of the earth.
- The temperature drops once again in this stratum, reaching its lowest point of -90 degrees Celsius on average. Despite the fact that this temperature can vary.
- From the troposphere to the mesosphere, there is a homogeneous layer. There is a layer of ions at the upper boundary of the mesosphere that extends into the other layer from the upper barrier. This layer of ions or charged particles is beneficial in that it reflects radio waves, which is useful in telecommunications applications.
- This is a region that stretches from 80 kilometres to 480 kilometres in length.
- It is surrounded by a functional ionosphere. As the gas molecules absorb the short wave radiation emitted by the sun, the temperature of this layer rises dramatically and rapidly.
- Because the density of the air in this layer is so low, the energy cannot be easily transferred, and as a result, the heat is not felt.
- This is the region where charged particles known as ions can be found. It extends from the upper mesosphere all the way to the high thermosphere.
- Ionisation of charged particles occurs by absorption of cosmic rays and gamma rays, as well as X-rays and UV radiation with shorter wavelengths.
- As a result of the friction created by arriving spacecraft and meteorites, the temperature of this layer begins to rise.
- Above this layer, or above 480 kilometres, atomic oxygen predominates, and beyond that, first helium becomes more abundant, and then hydrogen atoms take over as the dominant element.
- This layer of electrically charged molecules and atoms (known as ions) exists between 60 and 400 kilometres above the Earth’s surface in the middle and upper mesosphere and lower thermosphere, and it is located between 60 and 400 kilometres above the surface (40 and 250 miles).
The exosphere is the topmost layer of the atmosphere, located above the stratosphere.
Because of the absence of gravitational attraction, gases are extremely scarce in this realm. As a result, the density of the air is extremely low in this location.
With the decrease in altitude, there comes a change in pressure and density. However, the temperature does not change regularly. When the temperature changes concerning the distance, it is known as the Temperature gradient. Based on this temperature gradient, the atmosphere of Earth is widely divided into five layers. The source of Earth in each of these layers highlights the respective temperature gradient.
The planet Earth is not the only world that has a layer of atmosphere. In our solar system, there are atmospheres on all of the planets, as well as on a few of the moons. Clouds, wind, rain, and even tornadoes can be seen in some areas. Recently, scientists have begun to gain glimpses of the atmospheres of planets in other solar systems, which is an exciting development.
Earth’s current atmosphere has evolved over time, and its origins are not totally understood. According to current theories, the current atmosphere developed through the gradual release of gases from the planet’s interior as well as from the metabolic activities of life-forms, in contrast to the primordial atmosphere, which developed through outgassing (venting) during the planet’s initial formation.