The atmosphere is the layer of gases surrounding Earth. The air is an essential component of the earth's mass, and 99 percent of the total mass of the atmosphere is concentrated at a height of 32 kilometres above the earth's surface, held in place by gravity. Nitrogen and oxygen account for 99 percent of the gases in dry air, with argon, carbon dioxide, helium, neon, and other gases making up the remaining volume. The combination of gases in the atmosphere forms a complex system divided into layers that support life on Earth.<\/p>\r\n
The atmosphere can be divided into five layers - Troposphere, Ionosphere, Stratosphere, Exosphere, and Mesosphere. These atmospheric layers are characterised by variations in temperature resulting primarily from the absorption of solar radiation.<\/p>\r\n
Earth\u2019s atmosphere comprises about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases. The remaining 0.1% of gases includes a trace amount of neon, water vapour, carbon dioxide, methane and others. Water vapour and Carbon dioxide are found up to 90 km from the earth's surface.<\/p>\r\n
The atmosphere is divided into\u00a0five layers,\u00a0<\/strong>depending on temperature and density. In general, both temperature and density decrease with increasing altitude.<\/p>\r\n - The troposphere is the\u00a0lowest layer<\/strong>\u00a0and its average\u00a0height is 13 km<\/strong>\u00a0and extends roughly to a\u00a0height of 8 km near the poles<\/strong>\u00a0and about\u00a018 km at the equator<\/strong>.<\/p>\r\n - It is\u00a0thickest at the equator<\/strong>\u00a0because heat is transported to great heights by\u00a0strong convection currents<\/strong>\u00a0and much\u00a0thinner\u00a0<\/strong>at the\u00a0North and South Poles.\u00a0<\/strong><\/p>\r\n - Approximately\u00a075 and 80 percent of the mass<\/strong>\u00a0of the entire atmosphere is contained in the troposphere.<\/p>\r\n - Most of the\u00a0water vapour<\/strong>\u00a0in the\u00a0atmosphere<\/strong>, along with dust and ash particles, are found in the troposphere that\u2019s why most of\u00a0Earth\u2019s clouds<\/strong>\u00a0are located in this layer.<\/p>\r\n - Temperatures in the troposphere\u00a0decrease with altitude.<\/strong><\/p>\r\n Tropopause:<\/strong>\u00a0The\u00a0zone separating the troposphere from the stratosphere<\/strong>\u00a0is known as the tropopause.<\/p>\r\n - The stratosphere rises to a\u00a0height of 50 km<\/strong>, above the tropopause.<\/p>\r\n - It contains the\u00a0ozone layer<\/strong>\u00a0which absorbs\u00a0ultravioletradiation\u00a0<\/strong>and shields life on the earth from intense, harmful forms of\u00a0energy<\/strong>.<\/p>\r\n - Temperature\u00a0<\/strong>in the stratosphere\u00a0increases with altitude\u00a0<\/strong>as a result of heat that is produced during the\u00a0formation of ozone.<\/strong><\/p>\r\n - There is almost\u00a0no water vapour<\/strong>\u00a0in the stratosphere.<\/p>\r\n - Although the stratosphere is\u00a0nearly cloudy and weather-free<\/strong>, polar stratospheric clouds can occasionally be found at its lowest, coldest altitudes.<\/p>\r\n - It's the highest point in the atmosphere that\u00a0jet planes can access.<\/strong><\/p>\r\n - The top of the stratosphere is called the\u00a0stratopause<\/strong>.<\/p>\r\n<\/td>\r\n<\/tr>\r\n - It is located between\u00a050 and 80 kilometres<\/strong>\u00a0above the surface of the Earth.<\/p>\r\n - The\u00a0temperature\u00a0<\/strong>in the stratosphere\u00a0decreases with altitude.\u00a0<\/strong><\/p>\r\n - With a temperature of about\u00a0-90\u00b0C<\/strong>, the top of this layer is the\u00a0coldest place on Earth.<\/strong><\/p>\r\n - Noctilucent clouds (night-shining clouds) or\u00a0polar mesospheric clouds<\/strong>\u00a0are formed by the extremely rare water vapour that is found at the top of the mesosphere.<\/p>\r\n - Meteors\u00a0<\/strong>typically burn up in this layer of the atmosphere.<\/p>\r\n - Both\u00a0Sounding rockets<\/strong>\u00a0and\u00a0rocket-powered aircraft<\/strong>\u00a0are capable of reaching the mesosphere.<\/p>\r\n - The\u00a0upper boundary<\/strong>\u00a0of the mesosphere is called the\u00a0mesopause<\/strong>.<\/p>\r\n<\/td>\r\n<\/tr>\r\n - The Thermosphere is located between about\u00a080 and 700 kilometres<\/strong>\u00a0above Earth\u2019s surface<\/p>\r\n - The\u00a0ionosphere\u00a0<\/strong>(between 80 and 400 km) is a part of it.\u00a0<\/strong><\/p>\r\n - The Thermosphere is both\u00a0cloud and water-vapour-free.\u00a0<\/strong><\/p>\r\n - Here, one can occasionally see the\u00a0aurora australis<\/strong>\u00a0and\u00a0borealis<\/strong>.<\/p>\r\n - The\u00a0International Space Station orbits<\/strong>\u00a0in the thermosphere.<\/p>\r\n<\/td>\r\n<\/tr>\r\n - The topmost layer of Earth's atmosphere is known as the\u00a0exosphere<\/strong>.<\/p>\r\n - Located between about\u00a0700 and 10,000 kilometres\u00a0<\/strong>above the surface of the Earth.<\/p>\r\n - Because the molecules in this layer have a very\u00a0low density<\/strong>, this layer does not behave like gases and allows particles to escape into space.<\/p>\r\n - The\u00a0bottom of the exosphere<\/strong>\u00a0is also known as the exobase.\u00a0<\/strong><\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/figure>\r\n The atmosphere plays a crucial role in maintaining life on Earth. Without it, the temperature would fall well below the freezing point everywhere on the surface. The heat absorbed and trapped by the atmosphere helps regulate Earth\u2019s average temperature, making it suitable for living organisms. Gases such as carbon dioxide are particularly effective at absorbing and re-emitting infrared radiation, thereby warming the planet through the greenhouse effect.<\/p>\r\n Weather is a combination of events that occur in our atmosphere daily. The weather varies around the world and changes over a few minutes, hours, days, and weeks. The\u00a0troposphere<\/strong>, the region of Earth's atmosphere closest to the ground, is where most weather happens.<\/p>\r\n Climate refers to an area's average weather pattern over a long period. The weather is what we see outside on any particular day; the climate is the average of that weather. Different regions have different regional climates.<\/p>\r\n Question 1:\u00a0<\/strong>Troposphere is a very significant atmosphere layer that determines weather processes. How?\u00a0(UPSC Mains 2022)<\/strong><\/p>\r\n Question 2: <\/strong>Consider the following statements: (UPSC Prelims 2025)<\/strong><\/span><\/p>\r\n Which of the statements given above are correct?<\/span><\/p>\r\n a) 1 and 3 only<\/span><\/p>\r\n b) 1 and 2 only<\/span><\/p>\r\n c) 1, 2 and 3<\/span><\/p>\r\n d) 2 and 3 only<\/span><\/p>\r\n Ans: (d)<\/strong><\/p>\r\n Question 3: <\/strong>Normally, the temperature decreases with the increase in height from the Earth\u2019s surface, because\u00a0(UPSC Prelims 2012)<\/strong><\/p>\r\n Select the correct answer using the codes given below<\/p>\r\n a) <\/span>1 only<\/p>\r\n b) <\/span>2 and 3 only<\/p>\r\n c) <\/span>1 and 3 only<\/p>\r\n d) <\/span>1, 2 and 3<\/p>\r\n Answer: (c)<\/strong><\/p>\r\n Question 4: <\/strong>A layer in the Earth\u2019s atmosphere called Ionosphere facilitates radio communication. Why?\u00a0(UPSC Prelims 2011)<\/strong><\/p>\r\n Which of the statement(s) given above is\/are correct?<\/p>\r\n a) <\/span>1 only<\/p>\r\n b) <\/span>2 only<\/p>\r\n c) <\/span>Both 1 and 2<\/p>\r\n d) <\/span>Neither 1 nor 2<\/p>\r\n Answer: (d)<\/strong><\/p>\r\n\r\n\r\n
\r\n Layers of the Atmosphere<\/strong><\/td>\r\n<\/tr>\r\n \r\n Troposphere<\/strong><\/td>\r\n \r\n \r\n\t
\r\n Stratosphere<\/strong><\/td>\r\n \r\n \r\n Mesosphere<\/strong><\/td>\r\n \r\n \r\n Thermosphere<\/strong><\/td>\r\n \r\n \r\n\t
\r\n Exosphere<\/strong><\/td>\r\n \r\n Role of Atmosphere<\/h2>\r\n
Weather<\/h2>\r\n
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Climate<\/h2>\r\n
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Atmosphere UPSC PYQs<\/h2>\r\n
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\r\n Other Related Posts<\/strong><\/td>\r\n<\/tr>\r\n \r\n Geomorphology<\/strong><\/a><\/td>\r\n Major Dams in India<\/strong><\/a><\/td>\r\n<\/tr>\r\n \r\n