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4.4 Earth's Atmosphere

3 min readjune 14, 2023

Cody Williams

Cody Williams

Cody Williams

Cody Williams

Major Gases

The Earth's atmosphere is mostly composed of oxygen and nitrogen. Nitrogen (N2) is released into the atmosphere through (recall the !). Oxygen (O2) is released through and plants.

Water vapor (H2O) can also be a major gas in the atmosphere. It is notably more concentrated around the equator than around the poles (where humidity and tropic-like conditions are common).

There are also many other gases that play important roles in the atmosphere including methane (CH4), carbon dioxide (CO2), nitric oxide (N2O), and ozone (O3). Carbon dioxide, methane, and nitric oxide are all that trap heat in Earth’s atmosphere. All of these gases are released when are burned. Since humans have burned an abundance of , greenhouse gas emissions are high and our planet is warming.

Ozone (O3) absorbs harmful UV radiation given off by the sun. This layer reduces the amount of radiation that reaches the troposphere which is beneath the . The prevents a lot of negative side effects from the sun, but was significantly damaged by our use of CFCs (chlorofluorocarbons).

https://upload.wikimedia.org/wikipedia/commons/thumb/b/be/Top_of_Atmosphere.jpg/800px-Top_of_Atmosphere.jpg

Image Courtesy of Wikimedia

Layers of the Atmosphere

https://i.ibb.co/YphBfK5/Screen-Shot-2020-03-09-at-4-38-52-PM.png

The atmosphere is composed of the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. 

The first layer of the atmosphere (closest to the earth) is the troposphere. The troposphere starts at ground level and goes up to around 10 kilometers in altitude, about the average height of a cruising airplane. This layer is the shallowest layer of the atmosphere. Within this layer, temperature decreases as altitude increases, as all weather occurs in this atmospheric layer.

Above the troposphere is the stratosphere that goes from 10 kilometers in altitude to 50 kilometers in altitude. The stratosphere is mainly composed of Earth's , which is used for protection from UV rays. Thanks to the , the troposphere doesn’t receive 100% of the UV rays given off by the sun. This plays a big role in the temperature in the stratosphere, whose temperature increases with altitude unlike the troposphere,

Next is the mesosphere that goes from 50 kilometers to 80 kilometers in altitude. In this layer, the temperature decreases as you increase in altitude. This layer is very cold, and temperatures in the mesosphere can reach below -80 °C (-115 °F).

Then, the thermosphere goes from about 80 kilometers to 100 kilometers in altitude. Another name for the thermosphere is the ionosphere because this layer often traps protons, electrons, and other ions given off by the sun. As you increase in altitude in this layer, the temperature increases because this layer receives a lot of UV radiation and energy from the sun.

Finally, the exosphere is the highest layer of the Earth's atmosphere and is located around 700 and 10,000 km above Earth's surface. It is the upper limit of our atmosphere! At its top, it merges with the solar wind, and while no weather occurs here, the and can be seen at its lowest point. Many satellites orbit this layer of the atmosphere and the molecules in this layer have extremely low density.

🎥 Watch: AP Environmental Science Streams

Key Terms to Review (9)

Aurora Australis

: The Aurora Australis, also known as the Southern Lights, is a natural light display similar to the Aurora Borealis but occurs in the southern hemisphere near Antarctica.

Aurora Borealis

: The Aurora Borealis, also known as the Northern Lights, is a natural light display that occurs in the polar regions. It is caused by the interaction of charged particles from the sun with atoms in Earth's atmosphere.

Chlorofluorocarbons (CFCs)

: Chlorofluorocarbons (CFCs) are synthetic compounds made up of carbon, chlorine, and fluorine atoms. They were commonly used in aerosol propellants, refrigerants, and foam-blowing agents but have been phased out due to their harmful effects on the ozone layer.

Denitrification

: Denitrification is a natural process in which certain bacteria convert nitrates (NO3-) into nitrogen gas (N2), releasing it back into the atmosphere. It occurs primarily in oxygen-depleted environments, such as wetlands and soil.

Fossil Fuels

: Fossil fuels are energy-rich substances formed from ancient organic matter buried deep within the Earth's crust. They include coal, oil, and natural gas. Fossil fuels are burned to release energy but also release carbon dioxide and other pollutants into the atmosphere.

Greenhouse Gases

: Greenhouse gases are gases in the Earth's atmosphere that trap heat and contribute to the greenhouse effect, leading to global warming. They include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases.

Nitrogen Cycle

: The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms in the environment. It involves nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.

Ozone Layer

: The ozone layer is a region in Earth's stratosphere that contains a high concentration of ozone (O3) molecules. It plays a crucial role in absorbing and filtering out most of the sun's harmful ultraviolet (UV) radiation before it reaches the Earth's surface.

Photosynthesis

: Photosynthesis is the process through which green plants use sunlight, carbon dioxide, and water to produce glucose (sugar) and oxygen. It is vital for plant growth and releases oxygen into the atmosphere.

4.4 Earth's Atmosphere

3 min readjune 14, 2023

Cody Williams

Cody Williams

Cody Williams

Cody Williams

Major Gases

The Earth's atmosphere is mostly composed of oxygen and nitrogen. Nitrogen (N2) is released into the atmosphere through (recall the !). Oxygen (O2) is released through and plants.

Water vapor (H2O) can also be a major gas in the atmosphere. It is notably more concentrated around the equator than around the poles (where humidity and tropic-like conditions are common).

There are also many other gases that play important roles in the atmosphere including methane (CH4), carbon dioxide (CO2), nitric oxide (N2O), and ozone (O3). Carbon dioxide, methane, and nitric oxide are all that trap heat in Earth’s atmosphere. All of these gases are released when are burned. Since humans have burned an abundance of , greenhouse gas emissions are high and our planet is warming.

Ozone (O3) absorbs harmful UV radiation given off by the sun. This layer reduces the amount of radiation that reaches the troposphere which is beneath the . The prevents a lot of negative side effects from the sun, but was significantly damaged by our use of CFCs (chlorofluorocarbons).

https://upload.wikimedia.org/wikipedia/commons/thumb/b/be/Top_of_Atmosphere.jpg/800px-Top_of_Atmosphere.jpg

Image Courtesy of Wikimedia

Layers of the Atmosphere

https://i.ibb.co/YphBfK5/Screen-Shot-2020-03-09-at-4-38-52-PM.png

The atmosphere is composed of the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. 

The first layer of the atmosphere (closest to the earth) is the troposphere. The troposphere starts at ground level and goes up to around 10 kilometers in altitude, about the average height of a cruising airplane. This layer is the shallowest layer of the atmosphere. Within this layer, temperature decreases as altitude increases, as all weather occurs in this atmospheric layer.

Above the troposphere is the stratosphere that goes from 10 kilometers in altitude to 50 kilometers in altitude. The stratosphere is mainly composed of Earth's , which is used for protection from UV rays. Thanks to the , the troposphere doesn’t receive 100% of the UV rays given off by the sun. This plays a big role in the temperature in the stratosphere, whose temperature increases with altitude unlike the troposphere,

Next is the mesosphere that goes from 50 kilometers to 80 kilometers in altitude. In this layer, the temperature decreases as you increase in altitude. This layer is very cold, and temperatures in the mesosphere can reach below -80 °C (-115 °F).

Then, the thermosphere goes from about 80 kilometers to 100 kilometers in altitude. Another name for the thermosphere is the ionosphere because this layer often traps protons, electrons, and other ions given off by the sun. As you increase in altitude in this layer, the temperature increases because this layer receives a lot of UV radiation and energy from the sun.

Finally, the exosphere is the highest layer of the Earth's atmosphere and is located around 700 and 10,000 km above Earth's surface. It is the upper limit of our atmosphere! At its top, it merges with the solar wind, and while no weather occurs here, the and can be seen at its lowest point. Many satellites orbit this layer of the atmosphere and the molecules in this layer have extremely low density.

🎥 Watch: AP Environmental Science Streams

Key Terms to Review (9)

Aurora Australis

: The Aurora Australis, also known as the Southern Lights, is a natural light display similar to the Aurora Borealis but occurs in the southern hemisphere near Antarctica.

Aurora Borealis

: The Aurora Borealis, also known as the Northern Lights, is a natural light display that occurs in the polar regions. It is caused by the interaction of charged particles from the sun with atoms in Earth's atmosphere.

Chlorofluorocarbons (CFCs)

: Chlorofluorocarbons (CFCs) are synthetic compounds made up of carbon, chlorine, and fluorine atoms. They were commonly used in aerosol propellants, refrigerants, and foam-blowing agents but have been phased out due to their harmful effects on the ozone layer.

Denitrification

: Denitrification is a natural process in which certain bacteria convert nitrates (NO3-) into nitrogen gas (N2), releasing it back into the atmosphere. It occurs primarily in oxygen-depleted environments, such as wetlands and soil.

Fossil Fuels

: Fossil fuels are energy-rich substances formed from ancient organic matter buried deep within the Earth's crust. They include coal, oil, and natural gas. Fossil fuels are burned to release energy but also release carbon dioxide and other pollutants into the atmosphere.

Greenhouse Gases

: Greenhouse gases are gases in the Earth's atmosphere that trap heat and contribute to the greenhouse effect, leading to global warming. They include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases.

Nitrogen Cycle

: The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms in the environment. It involves nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.

Ozone Layer

: The ozone layer is a region in Earth's stratosphere that contains a high concentration of ozone (O3) molecules. It plays a crucial role in absorbing and filtering out most of the sun's harmful ultraviolet (UV) radiation before it reaches the Earth's surface.

Photosynthesis

: Photosynthesis is the process through which green plants use sunlight, carbon dioxide, and water to produce glucose (sugar) and oxygen. It is vital for plant growth and releases oxygen into the atmosphere.


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© 2024 Fiveable Inc. All rights reserved.

AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.