Fiveable
Fiveable

or

Log in

Find what you need to study


Light

Find what you need to study

Ozone Layer

3 min readdecember 6, 2021

Sitara H

Sitara H

Sitara H

Sitara H

Earths Atmosphere and The Stratospheric Ozone Layer

Overview

  • Ozone is a naturally occurring molecule made of three oxygen atoms (O3).

  • The ozone layer is the term for the highly-concentrated layer of ozone that can be found in the stratosphere, which is the second layer of atmosphere as you go upward and is found about 15-30km above the surface of the Earth. About 90 percent of the atmosphere’s ozone is contained within the stratosphere.

Ozone’s Benefits

The ozone layer covers the entire planet, and shields us by absorbing harmful ultraviolet-B (UV-B) radiation from the sun.

But why exactly is UV-B radiation bad? Well, UV-B radiation has been linked to skin conditions like sunburns, as well as skin cancers like basal cell carcinoma.

Basically, think of ozone as the Earth’s sunscreen!

The Ozone Hole

Through human industrial activity, chemicals containing atoms such as chlorine and bromine are released into the atmosphere. When combined with certain weather conditions such as high winds, this can lead to ozone molecules being destroyed.

Such thinning of the ozone layer has been occurring gradually around the globe, but the severe depletion over the Antarctic region is what is referred to as the “ozone hole”.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-vxVOi697WJ7u.png?alt=media&token=73cc5acd-b6c5-40c3-8245-71b8487b1f55

Image courtesy of Wikimedia

Causes

In 1974, a link between chlorofluorocarbons (CFCs) and the breakdown of ozone was discovered by chemists Mario Molina and Frank Sherwood Rowland.

A CFC is a molecule that contains the elements carbon, chlorine, and fluorine, which were present most famously in refrigerants and plastic products. They are, still to this day, used widely despite the harm they do to the environment, because they are cheap to acquire and relatively inflammable. When released into the air, CFCs make it very difficult for ozone to reform once it’s broken apart.

Over time, many other ozone-depleting substances have also been found in the atmosphere, such as halons, methyl bromide (CH3Br), hydrofluorocarbons (HCFCs), etc. They all work similarly, however-- they release chlorine and bromine atoms into the stratosphere, which destroys ozone molecules.

Consequences

The thinning of the ozone layer over the past few decades has also accelerated the process of global warming. Without a thick layer of ozone to protect us from UV-B radiation, these harmful parts of the sun’s radiation make their way into the lower parts of Earth’s atmosphere, where the presence of greenhouse gases such as carbon dioxide (CO2) and methane (CH4) prevent them from being reflected back out into space. As a result, this cycle gradually heats up the atmosphere, contributing to global warming. 🌍

Read more about Stratospheric Ozone Depletion

The Steps Being Taken 

Luckily, steps are being taken to preserve what is left of our ozone layer; so that it can hopefully replenish itself over time.

As early as 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer came into effect, which set obligations for countries to slowly stop producing all of the major ozone-depleting substances. Many other agreements were also made consequently. Every four years, the World Meteorological Organization (WMO) and the United Nations Environment Programme review the state of the ozone layer as well.

As a result of international action such as the Montreal Protocol and many others, the ozone layer is expected to recover to pre-1980 levels everywhere else by 2050, and over the polar regions by 2065.

Read more about Reducing Ozone Depletion

🤝Connect with other students studying Earth Science with Hours

Ozone Layer

3 min readdecember 6, 2021

Sitara H

Sitara H

Sitara H

Sitara H

Earths Atmosphere and The Stratospheric Ozone Layer

Overview

  • Ozone is a naturally occurring molecule made of three oxygen atoms (O3).

  • The ozone layer is the term for the highly-concentrated layer of ozone that can be found in the stratosphere, which is the second layer of atmosphere as you go upward and is found about 15-30km above the surface of the Earth. About 90 percent of the atmosphere’s ozone is contained within the stratosphere.

Ozone’s Benefits

The ozone layer covers the entire planet, and shields us by absorbing harmful ultraviolet-B (UV-B) radiation from the sun.

But why exactly is UV-B radiation bad? Well, UV-B radiation has been linked to skin conditions like sunburns, as well as skin cancers like basal cell carcinoma.

Basically, think of ozone as the Earth’s sunscreen!

The Ozone Hole

Through human industrial activity, chemicals containing atoms such as chlorine and bromine are released into the atmosphere. When combined with certain weather conditions such as high winds, this can lead to ozone molecules being destroyed.

Such thinning of the ozone layer has been occurring gradually around the globe, but the severe depletion over the Antarctic region is what is referred to as the “ozone hole”.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-vxVOi697WJ7u.png?alt=media&token=73cc5acd-b6c5-40c3-8245-71b8487b1f55

Image courtesy of Wikimedia

Causes

In 1974, a link between chlorofluorocarbons (CFCs) and the breakdown of ozone was discovered by chemists Mario Molina and Frank Sherwood Rowland.

A CFC is a molecule that contains the elements carbon, chlorine, and fluorine, which were present most famously in refrigerants and plastic products. They are, still to this day, used widely despite the harm they do to the environment, because they are cheap to acquire and relatively inflammable. When released into the air, CFCs make it very difficult for ozone to reform once it’s broken apart.

Over time, many other ozone-depleting substances have also been found in the atmosphere, such as halons, methyl bromide (CH3Br), hydrofluorocarbons (HCFCs), etc. They all work similarly, however-- they release chlorine and bromine atoms into the stratosphere, which destroys ozone molecules.

Consequences

The thinning of the ozone layer over the past few decades has also accelerated the process of global warming. Without a thick layer of ozone to protect us from UV-B radiation, these harmful parts of the sun’s radiation make their way into the lower parts of Earth’s atmosphere, where the presence of greenhouse gases such as carbon dioxide (CO2) and methane (CH4) prevent them from being reflected back out into space. As a result, this cycle gradually heats up the atmosphere, contributing to global warming. 🌍

Read more about Stratospheric Ozone Depletion

The Steps Being Taken 

Luckily, steps are being taken to preserve what is left of our ozone layer; so that it can hopefully replenish itself over time.

As early as 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer came into effect, which set obligations for countries to slowly stop producing all of the major ozone-depleting substances. Many other agreements were also made consequently. Every four years, the World Meteorological Organization (WMO) and the United Nations Environment Programme review the state of the ozone layer as well.

As a result of international action such as the Montreal Protocol and many others, the ozone layer is expected to recover to pre-1980 levels everywhere else by 2050, and over the polar regions by 2065.

Read more about Reducing Ozone Depletion

🤝Connect with other students studying Earth Science with Hours



© 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.


© 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.