Earth’s Atmosphere class 12: definition, layers, composition, and Diagram

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Earth’s atmosphere is a fascinating and complex system that plays a crucial role in supporting life on our planet. It’s the thin layer of gases that surrounds our planet, extending from the Earth’s surface up to an altitude of about 10,000 kilometers. This atmosphere is not only essential for breathing, but it also shields us from harmful solar radiation, regulates our climate, and enables important natural processes like the water cycle.

From the stunning auroras to the awe-inspiring thunderstorms, the Earth’s atmosphere is a dynamic and ever-changing system that continues to intrigue scientists and non-scientists alike. In this article, we will dive into the fascinating world of the Earth’s atmosphere, exploring its structure, layers, composition, and the amazing natural phenomena that occur within it.

What is the atmosphere?

The atmosphere is the layer of gases that surrounds the Earth. It is made up of a mix of different gases, including nitrogen, oxygen, carbon dioxide, and others. The atmosphere plays a vital role in regulating the Earth’s climate and weather patterns, protecting living organisms from harmful radiation, and providing the oxygen that is essential for life.

Earth’s Atmosphere: definition, layers, composition, and Diagram
Earth’s Atmosphere, source: Live Science

The atmosphere has several important functions, including:

  1. Providing oxygen for breathing: The atmosphere contains oxygen, which is essential for most forms of life on Earth.
  2. Regulating the Earth’s temperature: The atmosphere acts like a blanket, trapping heat from the sun and preventing it from escaping into space. This helps to regulate the Earth’s temperature and keep it within a range that is hospitable to life.
  3. Protecting against harmful radiation: The atmosphere also contains a layer of ozone in the stratosphere, which helps to absorb harmful ultraviolet radiation from the sun.
  4. Providing weather and climate: The atmosphere plays a key role in the formation of weather and climate patterns, by moving moisture and heat around the planet.

What is Earth’s Atmosphere definition?

Earth’s Atmosphere definition: Earth’s atmosphere is the layer of gases that surround our planet and is held in place by Earth’s gravity. It extends from the Earth’s surface up to an altitude of about 10,000 kilometers. It is composed mainly of nitrogen (about 78%), oxygen (about 21%), and other trace gases like argon, carbon dioxide, neon, helium, and methane.

The atmosphere plays a critical role in regulating Earth’s climate, protecting us from harmful solar radiation, and providing the oxygen that we breathe. It’s a dynamic and ever-changing system that is shaped by natural phenomena like weather patterns, volcanic eruptions, and human activities such as air pollution.

Structure of Earth’s Atmosphere

The Earth’s atmosphere can be divided into five layers based on their temperature, altitude, and composition. These layers, starting from the Earth’s surface and moving upwards, are:

  1. Troposphere: This is the lowest layer of the atmosphere, extending from the Earth’s surface up to an altitude of about 12 kilometers. The troposphere is where weather occurs, and it contains most of the Earth’s air mass. The temperature in this layer generally decreases with altitude.
  2. Stratosphere: The stratosphere extends from the top of the troposphere up to an altitude of about 50 kilometers. The ozone layer is located in the lower stratosphere and helps to absorb harmful ultraviolet radiation from the Sun. The temperature in the stratosphere generally increases with altitude.
  3. Mesosphere: The mesosphere extends from the top of the stratosphere up to an altitude of about 85 kilometers. This layer is characterized by extremely low temperatures and thin air. It’s also where many meteors burn up upon entering the Earth’s atmosphere.
  4. Thermosphere: The thermosphere extends from the top of the mesosphere up to an altitude of about 600 kilometers. This layer is characterized by high temperatures, reaching up to 2,000 degrees Celsius, and contains ionized gases that enable radio communication and the northern and southern lights.
  5. Exosphere: The exosphere is the outermost layer of the atmosphere, extending from the top of the thermosphere to the edge of space. The air in this layer is very thin, and it gradually merges with the vacuum of space.

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Different layers of Earth’s Atmosphere

The atmosphere can be divided into different strata based on temperature, as indicated in the diagram below. These layers are the troposphere, stratosphere, mesosphere, and thermosphere. The exosphere is a separate zone that begins roughly 500 kilometers above the Earth’s surface.

Earth’s Atmosphere: definition, layers, composition, and Diagram
Different layers of Earth’s Atmosphere, source: Leverage Edu

The different layers of Earth’s Atmosphere are discussed below:

  1. Troposphere: The troposphere is the lowest layer of Earth’s atmosphere, extending from the surface up to an altitude of about 12 kilometers. This layer is where all weather occurs, and it contains most of the Earth’s air mass. The temperature in this layer generally decreases with altitude, with an average temperature of about 15 degrees Celsius at the surface and -60 degrees Celsius at the top. The troposphere is also where most of the Earth’s greenhouse gases are found, including water vapor, carbon dioxide, and methane. These gases help to regulate the Earth’s temperature and keep it habitable for life.
  2. Stratosphere: The stratosphere extends from the top of the troposphere up to an altitude of about 50 kilometers. The stratosphere is characterized by a significant increase in temperature with altitude due to the presence of the ozone layer. The ozone layer is a region of the stratosphere where ozone gas (O3) is concentrated. This gas absorbs and filters out harmful ultraviolet radiation from the Sun, which can cause skin cancer and other health problems in humans. The temperature in the stratosphere generally increases with altitude due to the absorption of solar radiation by the ozone layer.
  3. Mesosphere: The mesosphere extends from the top of the stratosphere up to an altitude of about 85 kilometers. This layer is characterized by extremely low temperatures, with an average temperature of about -90 degrees Celsius at the top. The air in this layer is very thin, and the pressure is much lower than at the surface. The mesosphere is also where many meteors burn up upon entering the Earth’s atmosphere, creating the shooting stars that we see at night.
  4. Thermosphere: The thermosphere extends from the top of the mesosphere up to an altitude of about 600 kilometers. This layer is characterized by very high temperatures, reaching up to 2,000 degrees Celsius, due to the absorption of solar radiation by the ionized gases in this layer. The air in the thermosphere is very thin, and the pressure is almost zero. The ionized gases in this layer also enable radio communication and the northern and southern lights, which are beautiful displays of colored lights in the night sky caused by charged particles from the Sun interacting with the Earth’s magnetic field.
  5. Ionosphere: The ionosphere is a region within the thermosphere that is ionized by solar radiation. It is located between the mesosphere and the exosphere, extending from about 60 km to 1,000 km above the Earth’s surface. In the ionosphere, solar radiation causes the ionization of gas molecules and atoms, creating charged particles called ions. The ionosphere is therefore characterized by a high concentration of ions and free electrons, which can affect the propagation of radio waves and other forms of electromagnetic radiation. The ionosphere is an important region of the Earth’s atmosphere for radio communication and navigation, as it reflects and refracts radio waves back to the Earth’s surface, allowing for long-distance communication and global positioning. The ionosphere is also affected by solar activity, including solar flares and coronal mass ejections, which can disrupt radio communication and cause satellite and power grid failures.
  6. Exosphere: The exosphere is the outermost layer of Earth’s atmosphere, extending from the top of the thermosphere to the edge of space. The air in this layer is very thin, with a density of only a few particles per cubic centimeter. The exosphere gradually merges with the vacuum of space, and it’s where many satellites and other spacecraft orbit the Earth.

What is Magnetosphere?

The magnetosphere is the region around a planet, including the Earth, where the planet’s magnetic field dominates the behavior of charged particles, such as electrons and protons, in space. The Earth’s magnetosphere extends from the Earth’s surface out into space for thousands of kilometers.

Earth’s Atmosphere: definition, layers, composition, and Diagram
Earth’s Magnetosphere, source: NASA

The magnetosphere is created by the Earth’s magnetic field, which is generated by the motion of molten iron in the Earth’s core. The magnetic field lines of the Earth’s magnetic field are distorted by the solar wind, a stream of charged particles that flows out from the Sun. This distortion creates a protective shield around the Earth that helps to protect us from the harmful effects of the solar wind and other energetic particles in space.

The magnetosphere has several important properties and effects, including:

  • Particle trapping: The Earth’s magnetic field traps charged particles in the magnetosphere, creating two radiation belts (the Van Allen belts) that encircle the Earth. These belts are made up of high-energy particles, including electrons and protons, that can pose a hazard to satellites and other spacecraft that orbit the Earth.
  • Aurora: The interaction between the charged particles in the magnetosphere and the Earth’s upper atmosphere creates beautiful displays of light called auroras. Auroras occur when the charged particles collide with gas molecules in the atmosphere, causing them to emit light in different colors.
  • Shielding from the solar wind: The magnetosphere helps to shield the Earth from the harmful effects of the solar wind, including charged particles that can damage electronics on satellites and cause power outages on the ground.

Each layer of Earth’s atmosphere is important in its own way, and understanding the properties and dynamics of these layers is critical for many scientific and practical applications, including weather forecasting, climate modeling, and space exploration.

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Composition of the Earth’s Atmosphere

The Earth’s atmosphere is a complex mixture of gases, particles, and other materials that surround the planet and interact with the Earth’s surface, oceans, and biosphere. The composition of the Earth’s atmosphere is roughly 78% nitrogen, 21% oxygen, and 1% other gases and trace gases.

Here’s a more detailed breakdown of the composition of the Earth’s atmosphere:

  1. Nitrogen: Nitrogen gas (N2) is the most abundant gas in the Earth’s atmosphere, making up about 78% of the total volume. Nitrogen is a non-reactive gas and does not participate in most chemical reactions in the atmosphere.
  2. Oxygen: Oxygen gas (O2) is the second most abundant gas in the Earth’s atmosphere, making up about 21% of the total volume. Oxygen is essential for life on Earth, as it is used in cellular respiration by plants and animals to produce energy.
  3. Argon: Argon gas (Ar) is a noble gas that makes up about 0.9% of the Earth’s atmosphere. It is non-reactive and does not participate in most chemical reactions in the atmosphere.
  4. Carbon Dioxide: Carbon dioxide (CO2) is a trace gas in the Earth’s atmosphere, making up about 0.04% of the total volume. It is a greenhouse gas that helps to regulate the Earth’s temperature and is also essential for plant growth through the process of photosynthesis.
  5. Other gases: The remaining 0.1% of the Earth’s atmosphere is made up of a variety of other gases and trace gases, including methane (CH4), ozone (O3), water vapor (H2O), and neon (Ne), among others.

In addition to gases, the Earth’s atmosphere also contains small particles, such as dust, smoke, and pollen, as well as pollutants from human activities, such as carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen oxides (NOx).

Earth’s Atmosphere Facts

The Earth’s atmosphere is a fascinating and complex system that plays a vital role in sustaining life. Some interesting facts about the Earth’s atmosphere are given below:

  1. The atmosphere extends about 10,000 km above the Earth’s surface, but most of its mass is concentrated in the lower atmosphere, which extends about 10 km above the surface.
  2. The ozone layer is a thin layer of gas in the Earth’s stratosphere that absorbs harmful ultraviolet (UV) radiation from the Sun. Without the ozone layer, life on Earth would be exposed to dangerous levels of UV radiation.
  3. The Earth’s atmosphere is not evenly distributed around the planet. The atmosphere is denser at the equator than at the poles, and it is denser near the surface than at higher altitudes.
  4. The International Space Station (ISS) orbits within the Earth’s atmosphere, but it is still high enough to experience a small amount of atmospheric drag. As a result, the ISS loses altitude over time and needs periodic boosts to maintain its orbit.
  5. The Earth’s atmosphere is not static and is constantly changing due to a variety of natural and human-induced factors, including solar activity, volcanic eruptions, and air pollution.
  6. The Earth’s atmosphere is a vital component of the planet’s habitability, as it regulates temperature, protects us from harmful radiation, and provides oxygen for life to thrive.
  7. The Earth’s atmosphere is home to many fascinating weather phenomena, including thunderstorms, tornadoes, hurricanes, and the Northern and Southern Lights.
  8. Air pressure decreases with altitude, which is why people can experience altitude sickness when they travel to high altitudes.
  9. The Earth’s atmosphere also contains a layer of charged particles called the ionosphere, which is important for radio communication and navigation.
  10. The Earth’s atmosphere has a profound impact on the climate and is a major factor in global climate change.

Effects of Earth’s Atmosphere on the electromagnetic radiation

The Earth’s atmosphere plays a crucial role in affecting the propagation of electromagnetic radiation, including radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. Here are some of the effects of the Earth’s atmosphere on electromagnetic radiation:

  1. Absorption: Certain gases in the Earth’s atmosphere, such as water vapor, carbon dioxide, and ozone, are known to absorb certain wavelengths of electromagnetic radiation. This means that some frequencies of radiation are absorbed by the atmosphere before they can reach the Earth’s surface.
  2. Reflection: The Earth’s atmosphere can also reflect some frequencies of electromagnetic radiation back into space. This is particularly true of radio waves, which can be reflected by the ionosphere back to the Earth’s surface.
  3. Refraction: The Earth’s atmosphere can cause the bending or refraction of electromagnetic radiation as it passes through different layers of the atmosphere with varying densities. This can affect the way that radiation is transmitted and received, particularly for satellite communications.
  4. Scattering: The Earth’s atmosphere can scatter certain frequencies of electromagnetic radiation in different directions. This is why the sky appears blue during the daytime, as the blue wavelengths of sunlight are scattered more than other colors.

Understanding the effects of the Earth’s atmosphere on electromagnetic radiation is important for a range of applications, including satellite communication, remote sensing, weather forecasting, and astronomy. By studying the interactions between the atmosphere and electromagnetic radiation, scientists can gain insights into the properties and behavior of both the atmosphere and the radiation itself.

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What is the greenhouse effect?

The greenhouse effect is a natural process that occurs in the Earth’s atmosphere, which helps to regulate the temperature of the planet. It works by trapping heat from the sun that has been absorbed by the Earth’s surface and preventing it from escaping back into space.

Earth’s Atmosphere: definition, layers, composition, and Diagram
Greenhouse effects, source: Climate Change

Certain gases in the atmosphere, such as carbon dioxide (CO2), methane (CH4), and water vapor (H2O), act like a blanket around the Earth, trapping the heat that would otherwise radiate back into space. This process is similar to the way that a greenhouse traps heat, hence the name “greenhouse effect.”

Without the greenhouse effect, the Earth’s surface temperature would be much colder, making it difficult for life to exist as we know it. However, human activities such as burning fossil fuels and deforestation have increased the concentration of greenhouse gases in the atmosphere, leading to an enhanced greenhouse effect and causing global temperatures to rise.

The enhanced greenhouse effect, also known as global warming, has significant consequences for the planet, including sea level rise, increased frequency and intensity of extreme weather events, and changes in ecosystems and biodiversity. Therefore, it is important to take action to reduce greenhouse gas emissions and mitigate the effects of climate change.

Importance of the Ozone layer

The ozone layer is a region of the Earth’s atmosphere that contains a high concentration of ozone (O3) molecules. It is located in the stratosphere, about 10-50 kilometers above the Earth’s surface. The ozone layer plays a crucial role in protecting life on Earth by absorbing harmful ultraviolet (UV) radiation from the sun.

Earth’s Atmosphere: definition, layers, composition, and Diagram
The ozone layer, source: News Medical

Here are some of the key reasons why the ozone layer is so important:

  1. Protection from UV radiation: The ozone layer absorbs most of the sun’s harmful UV radiation, which can cause skin cancer, cataracts, and other health problems in humans and other organisms. Without the ozone layer, the Earth’s surface would be exposed to much higher levels of UV radiation, making life much more difficult and potentially dangerous.
  2. Climate regulation: Ozone is a greenhouse gas, which means that it can help to regulate the temperature of the Earth’s atmosphere by trapping heat. However, unlike other greenhouse gases such as carbon dioxide, ozone is mostly concentrated in the stratosphere and does not contribute significantly to global warming.
  3. Protection of ecosystems: The ozone layer also plays an important role in protecting ecosystems by shielding plants and animals from the harmful effects of UV radiation. UV radiation can damage or kill plants and phytoplankton, which are important sources of food and oxygen for many other organisms.

However, the ozone layer is currently under threat from human activities, such as the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances. These substances break down ozone molecules in the stratosphere, leading to the formation of the “ozone hole” over Antarctica and other regions. Therefore, it is important to continue to monitor and reduce the use of these substances in order to protect the ozone layer and the many benefits it provides.

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Importance of Earth’s Atmosphere

The Earth’s atmosphere is important for a number of reasons. Here are a few of the key ways in which it plays a vital role:

  1. Climate regulation: The atmosphere helps to regulate the Earth’s temperature by trapping heat from the sun and preventing it from escaping back into space. This is known as the greenhouse effect, and it helps to keep the Earth’s surface warm enough to support life.
  2. Protection from radiation: The atmosphere also helps to protect the Earth from harmful radiation from the sun and other sources. The ozone layer in the stratosphere, for example, helps to absorb harmful ultraviolet radiation that can cause skin cancer and other health problems.
  3. Weather patterns: The atmosphere plays a key role in shaping weather patterns around the world. By circulating heat and moisture around the planet, the atmosphere helps to create the conditions that lead to precipitation, winds, and other weather phenomena.
  4. Support for life: The atmosphere is essential for supporting life on Earth, as it provides the oxygen that is needed for respiration and helps to regulate the Earth’s temperature and weather patterns. Without the atmosphere, life as we know it would not be possible.

Frequently Asked Questions – FAQs

What is the atmosphere?

The atmosphere is the layer of gases that surrounds the Earth. It is made up of a mix of different gases, including nitrogen, oxygen, carbon dioxide, and others.

Nitrogen percentage in the atmosphere

The percentage of nitrogen in the Earth’s atmosphere is approximately 78%. This makes nitrogen the most abundant gas in the atmosphere by far.

Carbon dioxide percentage in the atmosphere

CO2 makes up only about 0.04% of the atmosphere.

How many layers are in the atmosphere?

The Earth’s atmosphere is typically divided into five layers, based on differences in temperature, pressure, and composition.

5 layers of the atmosphere

The 5 layers of Earth’s atmosphere from the ground up are:

Troposphere: This is the lowest layer of the atmosphere, extending from the Earth’s surface up to an altitude of about 7 to 20 kilometers (depending on location and season). It is where weather occurs and contains about 80% of the atmosphere’s mass.

Stratosphere: Above the troposphere is the stratosphere, which extends up to an altitude of about 50 kilometers. The stratosphere contains the ozone layer, which absorbs harmful ultraviolet radiation from the sun.

Mesosphere: Above the stratosphere is the mesosphere, which extends up to an altitude of about 85 kilometers. This is the layer where meteors burn up as they enter the Earth’s atmosphere.

Thermosphere: The thermosphere is above the mesosphere, extending up to an altitude of about 600 kilometers. It is a very thin layer, but it experiences high temperatures due to the absorption of solar radiation.

Exosphere: This is the outermost layer of the atmosphere, extending from the top of the thermosphere out into space. It is a very thin layer and contains mainly helium and hydrogen atoms, as well as some heavier gases.

What is Earth’s atmosphere made up of?

The Earth’s atmosphere is made up of a mixture of gases, primarily nitrogen (about 78%) and oxygen (about 21%). The remaining 1% is composed of trace gases such as carbon dioxide, helium, neon, methane, and ozone, as well as water vapor, which can vary widely depending on location and weather conditions.

In addition to gases, the atmosphere also contains small solid and liquid particles such as dust, salt, and water droplets, collectively known as aerosols. These particles play an important role in scattering and absorbing sunlight, as well as providing surfaces for chemical reactions to occur.

Gases in Earth’s atmosphere

The gases in Earth’s atmosphere, along with their approximate percentages by volume, are:

Nitrogen (N2): 78%
Oxygen (O2): 21%
Argon (Ar): 0.93%
Carbon dioxide (CO2): 0.04%
Neon (Ne): 0.0018%
Helium (He): 0.0005%
Methane (CH4): 0.0002%
Krypton (Kr): 0.0001%
Hydrogen (H2): traces
Nitrous oxide (N2O): traces
Ozone (O3): traces
Water vapor (H2O): highly variable, typically between 0.1% and 1%

It’s worth noting that these percentages can vary slightly depending on location, altitude, and other factors. Additionally, the atmosphere also contains various pollutants and other trace gases in very small amounts, some of which can have significant impacts on human health and the environment.

Stay tuned with Laws Of Nature for more useful and interesting content.

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