{"id":15812,"date":"2026-06-13T05:08:20","date_gmt":"2026-06-12T23:38:20","guid":{"rendered":"https:\/\/ibexaviation.com\/pilot-training\/?p=15812"},"modified":"2026-07-26T10:41:17","modified_gmt":"2026-07-26T05:11:17","slug":"layers-of-atmosphere","status":"publish","type":"post","link":"https:\/\/ibexaviation.com\/pilot-training\/layers-of-atmosphere\/","title":{"rendered":"Layers of Atmosphere"},"content":{"rendered":"<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-1.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<h2>Introduction to Layers of the Atmosphere<\/h2>\n<p>The atmosphere is the blanket of gases that surrounds the Earth and supports life. It is divided into different layers based on changes in temperature and altitude. The atmosphere is divided into five main layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has unique characteristics and plays an important role in protecting our planet.<\/p>\n<h3>Earth&#8217;s Atmosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-2.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The Earth is surrounded by a gaseous envelope known as the atmosphere, which extends up to approximately <strong>800 km<\/strong> above the Earth&#8217;s surface.<\/p>\n<p>This atmosphere remains attached to the Earth due to gravitational force and rotates at the same speed as the planet.<\/p>\n<h3>Composition of Atmosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-3.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The atmosphere is primarily composed of:<\/p>\n<ul>\n<li>78% Nitrogen<\/li>\n<li>21% Oxygen<\/li>\n<li>1% Trace Gases<\/li>\n<\/ul>\n<p>The ratio of Nitrogen to Oxygen is:<\/p>\n<ul>\n<li>4:1 by volume<\/li>\n<li>3:1 by weight<\/li>\n<\/ul>\n<p>As altitude increases, the concentration of oxygen decreases. Supplemental oxygen is therefore required for humans at altitudes above <strong>10,000 feet<\/strong>.<\/p>\n<h3>Homosphere and Heterosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-4.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The atmosphere is divided into two major regions:<\/p>\n<ul>\n<li><strong>Homosphere:<\/strong> Extends up to about 80 km, where the composition of gases remains relatively constant.<\/li>\n<li><strong>Heterosphere:<\/strong> Exists above 80 km, where the composition of gases varies with altitude.<\/li>\n<\/ul>\n<h3>Density of Air in the Atmosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-5.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>Air density is highest at the Earth&#8217;s surface and gradually becomes thinner at higher altitudes.<\/p>\n<p>The distribution of atmospheric air mass is as follows:<\/p>\n<ul>\n<li>50% of the atmosphere lies below 6 km<\/li>\n<li>75% lies below 10 km<\/li>\n<li>99% lies below 35 km<\/li>\n<\/ul>\n<p>The atmosphere contains a small percentage of water vapour that plays an important role in weather, climate, and environmental processes.<\/p>\n<h3>Trace Gases in the Atmosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-6.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The major trace gases present in the atmosphere include:<\/p>\n<ul>\n<li>Argon (0.93%)<\/li>\n<li>Carbon Dioxide (0.035%)<\/li>\n<li>Neon<\/li>\n<li>Methane<\/li>\n<li>Helium<\/li>\n<li>Ozone<\/li>\n<li>Hydrogen<\/li>\n<li>Krypton<\/li>\n<li>Xenon<\/li>\n<li>Nitrogen Dioxide (NO\u2082)<\/li>\n<li>Iodine<\/li>\n<li>Carbon Monoxide (CO)<\/li>\n<li>Sulphur Dioxide (SO\u2082)<\/li>\n<li>Variable Gases<\/li>\n<\/ul>\n<h3>Variable Gases in the Atmosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-7.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>Certain gases in the atmosphere vary in concentration depending on location, weather conditions, and human activities. These include:<\/p>\n<ul>\n<li>Water Vapour<\/li>\n<li>Carbon Monoxide (CO)<\/li>\n<li>Sulphur Dioxide (SO\u2082)<\/li>\n<li>Nitrogen Dioxide (NO\u2082)<\/li>\n<li>Methane<\/li>\n<\/ul>\n<p>Greenhouse gases partially absorb long-wave radiation emitted by the Earth, helping to maintain the planet&#8217;s temperature. However, an excess concentration of greenhouse gases leads to global warming.<\/p>\n<h3>Carbon Dioxide and Solid Particles<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-8.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>Solid particles such as sea salt, dust, and smoke are found in the atmosphere.<\/p>\n<p>These particles can contribute to the formation of smog and affect air quality and visibility.<\/p>\n<p>Carbon dioxide (CO\u2082) is mainly produced by the burning of fuels.<\/p>\n<ul>\n<li>Plants help reduce atmospheric CO\u2082 by absorbing it during photosynthesis.<\/li>\n<\/ul>\n<h3>Ozone Layer<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-9.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The ozone layer is found in the upper atmosphere between <strong>10 km and 50 km<\/strong>, with maximum concentration occurring between <strong>20 km and 25 km<\/strong>.<\/p>\n<p>The ozone layer plays a crucial role by absorbing harmful ultraviolet (UV) radiation from the Sun, thereby protecting life on Earth.<\/p>\n<h3>Thermal Structure of the Atmosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-10.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Short-wave solar radiation reaches the Earth&#8217;s surface by passing through the atmosphere.<\/li>\n<li>The atmosphere is heated by re-radiation from the Earth, known as <strong>terrestrial radiation<\/strong>.<\/li>\n<li>Sensible heat is transferred by <strong>conduction, convection,<\/strong> and <strong>radiation<\/strong>.<\/li>\n<li>Latent heat is transferred through <strong>evaporation, condensation,<\/strong> and <strong>sublimation<\/strong>.<\/li>\n<\/ul>\n<h3>Saturation of Air<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-11.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Air is saturated when it holds the maximum possible water vapour at a given temperature.<\/li>\n<li>Saturation requires approximately 4% water vapour.<\/li>\n<li>Relative Humidity (RH) is 100% in saturated air.<\/li>\n<li>Unsaturated air contains less than 4% water vapour.<\/li>\n<li>Relative Humidity is less than 100% in unsaturated air.<\/li>\n<li>Higher temperatures require more water vapour for saturation.<\/li>\n<li>In tropical regions about 4% water vapour is required for saturation.<\/li>\n<li>Near the poles, only negligible water vapour is sufficient for saturation.<\/li>\n<\/ul>\n<h2>Troposphere and Tropopause have the maximum effect on Civil Aviation<\/h2>\n<h3>Troposphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-12.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The troposphere is the lowest layer of the atmosphere.<\/li>\n<li>Most weather phenomena occur here due to the presence of water vapour.<\/li>\n<li>Commercial flying and atmospheric disturbances are mainly confined to this region.<\/li>\n<li>Temperature generally decreases with height.<\/li>\n<li>Average lapse rate is <strong>6.5\u00b0C per km<\/strong>.<\/li>\n<li>Temperature increases with height in an <strong>inversion layer<\/strong>.<\/li>\n<li>In an <strong>isothermal layer<\/strong>, temperature remains constant with height.<\/li>\n<\/ul>\n<h3>Tropopause<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-13.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The tropopause is the upper boundary of the troposphere.<\/li>\n<li>Average height: <strong>11 km<\/strong>.<\/li>\n<li>Nearly an isothermal layer.<\/li>\n<li>Equatorial Tropopause: <strong>16\u201318 km<\/strong>, temperature around <strong>\u221270\u00b0C<\/strong>.<\/li>\n<li>Polar Tropopause: <strong>8\u201310 km<\/strong>, temperature around <strong>\u221250\u00b0C<\/strong>.<\/li>\n<\/ul>\n<h3>Variation in Tropopause with Latitude<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-14.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Tropopause height decreases with increasing latitude.<\/li>\n<li>Tropopause temperature increases with latitude.<\/li>\n<li>Jet streams and Clear Air Turbulence (CAT) are commonly found near the tropopause.<\/li>\n<li>Temperature inversion or isothermal conditions may occur near the tropopause.<\/li>\n<li>Tropopause temperature is lower at the equator than at the poles.<\/li>\n<\/ul>\n<h3>Factors Affecting Tropopause Height<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-15.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>Height and temperature of the tropopause depend on:<\/p>\n<ul>\n<li>Surface temperature<\/li>\n<li>Latitude<\/li>\n<li>Season<\/li>\n<li>Land\u2013sea distribution<\/li>\n<li>Synoptic weather conditions<\/li>\n<\/ul>\n<p>Seasonal variations:<\/p>\n<ul>\n<li>Tropopause is generally lower during winter than during summer.<\/li>\n<li>Near the poles, temperature and density reversal occur above 8 km, causing temperature to increase with height.<\/li>\n<\/ul>\n<h3>Breaks in the Tropopause<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-16.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>Distinct breaks in temperature and thickness occur around:<\/p>\n<ul>\n<li>40\u00b0 Latitude<\/li>\n<li>60\u00b0 Latitude (mainly during winter)<\/li>\n<\/ul>\n<p>These are associated with:<\/p>\n<ul>\n<li>Hadley Cell<\/li>\n<li>Ferrel Cell<\/li>\n<li>Polar Cell<\/li>\n<\/ul>\n<p>Jet streams are commonly found near these breaks.<\/p>\n<h3>Types of Tropopause<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-17.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<h3>Tropical Tropopause<\/h3>\n<ul>\n<li>Extends from the Equator to about 35\u00b0\u201340\u00b0 latitude.<\/li>\n<li>Pressure level: 100 hPa.<\/li>\n<li>Height: Approximately 16 km.<\/li>\n<li>Dominates over India up to 35\u00b0N.<\/li>\n<\/ul>\n<h3>Subtropical Tropopause<\/h3>\n<ul>\n<li>Occurs between 40\u00b0\u201360\u00b0 latitude.<\/li>\n<li>Pressure level: 200 hPa.<\/li>\n<li>Height: Approximately 12 km.<\/li>\n<li>Subtropical Jet Stream occurs near its southern boundary.<\/li>\n<\/ul>\n<h3>Polar Tropopause<\/h3>\n<ul>\n<li>Extends from 60\u00b0 latitude to the poles.<\/li>\n<li>Pressure level: 300 hPa.<\/li>\n<\/ul>\n<h2>Layers above Tropopause that have limited impact on Civil Aviation<\/h2>\n<h3>Stratosphere and Stratopause<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-18.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Extends from the tropopause to about 50 km.<\/li>\n<li>Contains a high concentration of ozone.<\/li>\n<li>Temperature increases with height due to ozone absorption of solar radiation.<\/li>\n<li>Stable atmospheric layer with little humidity or weather activity.<\/li>\n<li>Nacreous (Mother-of-Pearl) clouds may occur.<\/li>\n<li>The upper boundary is called the <strong>Stratopause<\/strong>.<\/li>\n<\/ul>\n<h3>Mesosphere and Mesopause<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-19.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Extends from the stratopause to 80\u201390 km.<\/li>\n<li>Temperature decreases with height.<\/li>\n<li>Noctilucent clouds occur near the poles.<\/li>\n<li>Mesopause temperature is approximately <strong>\u221290\u00b0C to \u2212100\u00b0C<\/strong>.<\/li>\n<\/ul>\n<h3>Thermosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-20.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Begins above the mesosphere.<\/li>\n<li>Temperature increases rapidly with height.<\/li>\n<li>Typical temperatures range from <strong>600\u00b0C to 2000\u00b0C<\/strong>.<\/li>\n<\/ul>\n<h3>Ionosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-21.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The ionosphere extends upward from around 60 km and is essential for radio communication.<\/p>\n<p>It contains free electrons and is divided into:<\/p>\n<ul>\n<li>D Layer \u2013 Kennelly Layer (~110 km)<\/li>\n<li>E Layer \u2013 Heaviside Layer (~160 km)<\/li>\n<li>F Layer \u2013 Appleton Layer (~250 km)<\/li>\n<\/ul>\n<h3>Exosphere<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-22.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Begins above approximately 700 km.<\/li>\n<li>Extremely low air density.<\/li>\n<li>Gradually merges into outer space.<\/li>\n<\/ul>\n<h2>Definition and need for ISA Conditions<\/h2>\n<h3>International Standard Atmosphere (ISA)<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-23.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The International Standard Atmosphere (ISA) was defined by the International Civil Aviation Organisation (ICAO).<\/p>\n<p>Applications:<\/p>\n<ul>\n<li>Standard reference for aviation below 30,000 ft.<\/li>\n<li>Aircraft design and testing.<\/li>\n<li>Calibration of aircraft instruments.<\/li>\n<\/ul>\n<h3>Mean Sea Level ISA Conditions<\/h3>\n<ul>\n<li>Temperature: +15\u00b0C<\/li>\n<li>Pressure: 1013.25 hPa<\/li>\n<li>Density: 1225 g\/m\u00b3<\/li>\n<li>Gravity: 9.80665 m\/s\u00b2<\/li>\n<\/ul>\n<p>ISA is defined up to <strong>146,000 ft (42.6 km)<\/strong>.<\/p>\n<h3>ISA Lapse Rate<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-24.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Decreases by 1.98\u00b0C per 1000 ft up to 11 km (36,090 ft).<\/li>\n<li>Constant at \u221256.5\u00b0C up to 20 km (65,617 ft).<\/li>\n<li>Increases by 1\u00b0C per km thereafter.<\/li>\n<li>Constant at \u221244.5\u00b0C around 32 km (104,987 ft).<\/li>\n<\/ul>\n<p><strong>ISA Deviation = Actual Temperature \u2212 ISA Temperature<\/strong><\/p>\n<h3>Jet Standard Atmosphere (JSA)<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m1-layers-of-atmosphere-25.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p>The Jet Standard Atmosphere (JSA) is defined for high-level flight operations and spacecraft testing.<\/p>\n<h3>Mean Sea Level JSA Conditions<\/h3>\n<ul>\n<li>Temperature: +15\u00b0C<\/li>\n<li>Pressure: 1013.25 hPa<\/li>\n<li>Density: 1225 g\/m\u00b3<\/li>\n<li>Gravity: 9.80665 m\/s\u00b2<\/li>\n<\/ul>\n<h3>JSA Lapse Rate<\/h3>\n<ul>\n<li>Temperature decreases at 2\u00b0C per 1000 ft.<\/li>\n<li>Tropopause is absent in the JSA model.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Introduction to Layers of the Atmosphere The atmosphere is the blanket of gases that surrounds the Earth and supports life. It is divided into different layers based on changes in temperature and altitude. The atmosphere is divided into five main layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has unique characteristics and plays an important role in protecting our planet. Earth&#8217;s Atmosphere The Earth is surrounded by a gaseous envelope known as the atmosphere, which extends up to approximately 800 km above the Earth&#8217;s surface. This atmosphere remains&hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"disable_featured_image":false,"footnotes":""},"categories":[358],"tags":[],"class_list":["post-15812","post","type-post","status-publish","format-standard","hentry","category-aviation-meteorology"],"_links":{"self":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/15812","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/comments?post=15812"}],"version-history":[{"count":1,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/15812\/revisions"}],"predecessor-version":[{"id":16674,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/15812\/revisions\/16674"}],"wp:attachment":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/media?parent=15812"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/categories?post=15812"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/tags?post=15812"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}