The Earth's atmosphere is the gaseous layer surrounding our planet... Show more
Chemistry232 views·Updated May 10, 2026·4 pagesGCSE Chemistry Notes: Atmosphere - Topic 9 AQA Overview
1 / 4
1
of 4
The Atmosphere's Composition
Our atmosphere today consists mostly of nitrogen (78%) and oxygen (21%), with small amounts of other gases including carbon dioxide, water vapour and noble gases. This composition has remained relatively stable for about 200 million years, but it wasn't always this way.
During Earth's first billion years, intense volcanic activity released gases that formed the early atmosphere, primarily water vapour and carbon dioxide. As the planet cooled, water vapour condensed to form oceans, but carbon dioxide remained dominant in the atmosphere—similar to what we see today on Mars and Venus.
Carbon dioxide levels decreased over time through several natural processes. The gas dissolved in oceans, creating a weak acid that reacted with minerals to form precipitates. These eventually became sediments of carbonate rock on the sea bed. Marine organisms like corals and mussels also used carbon dioxide to create their shells, which later formed limestone when they died.
Did you know? The limestone formations we see today represent carbon dioxide that was once in the atmosphere, showing how Earth naturally sequestered carbon over millions of years!
2
of 4
The Rise of Oxygen and Fossil Fuels
About 1.7 billion years ago, a major atmospheric shift began when photosynthetic algae evolved in the oceans. These simple organisms produced oxygen as a byproduct of photosynthesis. As plants later evolved on land, oxygen levels continued to increase until they reached a point where animal life could develop.
While oxygen levels rose, carbon dioxide was being trapped in what we now call fossil fuels. Coal formed when plant material in marshy wetlands didn't fully decompose due to lack of oxygen or acidic conditions. Under high pressure and temperature over millions of years, this plant matter transformed into coal.
Crude oil and natural gas formed similarly but from marine organisms. When plankton died and settled in mud on the sea floor, their remains were preserved without decomposition if oxygen was absent. Gradually, heat and pressure transformed these remains—plankton became crude oil, while natural gas (primarily methane) often formed nearby.
Important: The greenhouse effect is actually natural and necessary! Without it, Earth would be too cold for life. Gases like carbon dioxide, water vapour and methane trap the sun's heat by allowing short-wavelength radiation in but absorbing the long-wavelength radiation that the Earth radiates back.
3
of 4
Climate Change and Solutions
Human activities have significantly altered atmospheric composition, particularly through deforestation and fossil fuel use. Cutting down forests not only removes carbon-absorbing trees but also releases stored CO₂. Meanwhile, agriculture—especially cattle farming—produces large amounts of methane, another powerful greenhouse gas.
The impacts of these changes are already visible: melting polar ice, rising sea levels, more severe weather patterns, and shifting distributions of plants, animals and diseases like malaria. While climate models are complex and sometimes lead to simplified predictions, the evidence for human-caused climate change is overwhelming.
Reducing our carbon footprint—the total amount of greenhouse gases produced through our activities—requires both individual and societal changes. Simple steps include better home insulation, using public transport instead of cars, switching to renewable energy sources, and reducing electricity consumption. Eating less beef and dairy also helps reduce methane emissions.
Take action: Calculate your personal carbon footprint online to see which of your daily activities contribute most to greenhouse gas emissions. You might be surprised by what makes the biggest impact!
4
of 4
Air Pollution from Fuels
When we burn fossil fuels like coal and hydrocarbons, they release several harmful pollutants. The carbon and hydrogen in these fuels react with oxygen in the air to produce various compounds, some quite dangerous to human health.
Carbon monoxide is a toxic gas produced by incomplete combustion. It has no colour or smell, making it particularly dangerous—which is why carbon monoxide detectors in homes are so important. When coal containing sulfur is burned, it produces sulfur dioxide, which causes breathing problems and contributes to acid rain.
Vehicles create another set of pollutants. The high temperatures in car engines cause nitrogen and oxygen in the air to react, forming various nitrogen oxides (NOx). These, along with sulfur dioxide, dissolve in rainwater to create acid rain that damages trees and buildings. Cars also release particulates—tiny unburned hydrocarbon particles that increase the risk of heart and lung disease.
Health alert: Air pollution isn't just an environmental issue—it's a major health concern. The World Health Organization estimates that air pollution contributes to millions of premature deaths annually, primarily from respiratory and cardiovascular diseases.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: Atmospheric Chemistry
5ChemistryAQA GCSE Chemistry Revision
Comprehensive revision notes for AQA GCSE Chemistry Paper 2, covering key topics such as organic chemistry, environmental chemistry, chemical reactions, and the structure of DNA. Ideal for higher-tier students preparing for exams, this resource includes essential concepts like hydrocarbons, equilibrium, and sustainable development.
91,72349
ChemistryGreenhouse Gases Overview
Explore the chemistry of the atmosphere with a focus on greenhouse gases, their sources, and effects on climate change. This summary covers key concepts such as the greenhouse effect, carbon dioxide, methane, and the impact of human activities like fossil fuel combustion and deforestation. Ideal for GCSE students studying Topic 9.
93148
ChemistryOrganic Chemistry Insights
Explore key concepts in organic chemistry, including hydrocarbons, chemical reactions, and equilibrium. This mind map covers essential topics for AQA Chemistry Paper 2, such as the properties of hydrocarbons, cracking processes, and the impact of chemical resources on the environment. Ideal for students preparing for exams, this resource provides a clear overview of atmospheric chemistry, rates of reaction, and water resource management.
1149116
ChemistryChemistry of the atmosphere
Triple aqa gcse
11520
ChemistryEarth's Atmospheric Evolution
Explore the formation and evolution of Earth's atmosphere, focusing on volcanic activity, the rise of oxygen through photosynthesis, and the decrease of carbon dioxide. This summary covers key concepts in atmospheric chemistry relevant for GCSE Higher Chemistry students.
112361
Most popular content in Chemistry
9G
ChemistryGCSE AQA Chemistry Topic 1- The Atom
The Atom
109220
Chemistrychem paper 1
higher
111,79137
G
ChemistryGCSE AQA Chemistry Topic 1
Quiz covering all of topic 1
101,6573
ChemistryA-level OCR A Chemistry summary sheets
Everything from snaprevise for OCR chemistry a-level
121,98677
ChemistryEssential Chemistry Practicals
Explore key AQA GCSE Chemistry practicals, including flame tests, titration, and gas identification. This resource covers essential techniques for analyzing ions, making salts, and understanding reaction kinetics. Perfect for students preparing for exams and practical assessments.
1011,774902
C
Chemistrychem paper 1
Unlock the secrets of chemical reactions with this comprehensive flashcard set designed to help you conquer complex concepts and ace your Chemistry exams.
115831
A
ChemistryAQA GCSE Chemistry 4.2 Bonding, structure and the Properties of Matter
4.2 Metals and Alloys
96720
A
ChemistryAQA GCSE Chemistry 4.4 Chemical changes
4.4 Reactions of acids with bases or carbonates
95481
F
ChemistryFundamentals of Atomic Structure
Practice identifying subatomic particles, calculating neutrons, and defining isotopes and atomic/mass numbers.
123380
Most popular content
9
SociologySociology of Education Overview
Explore comprehensive A-Level Sociology notes on the education system, covering key theories, policies, and sociological perspectives. This resource includes insights on marketisation, gender roles, cultural deprivation, and educational inequalities, providing a thorough understanding of how education shapes social stratification and individual achievement. Ideal for exam preparation and in-depth study.
12101,9373,035
SociologySociology of Families: Comprehensive Revision
Dive into an extensive overview of family dynamics, perspectives, and patterns in sociology. This resource covers key concepts such as family diversity, gender roles, marriage, and the impact of social policies on family structures. Perfect for A-Level Sociology students preparing for Paper 2.
1271,4942,280
English LiteratureAn Inspector Calls: Character Insights
Explore in-depth analysis and key quotes for characters in J.B. Priestley's 'An Inspector Calls'. This resource covers Gerald Croft, Inspector Goole, Sheila Birling, Mrs. Birling, Eric Birling, and Eva Smith, focusing on themes of class, gender roles, and social responsibility. Ideal for students aiming for Grade 8 and above.
1025,037896
CriminologyCriminology: Crime & Punishment Overview
Comprehensive mindmaps covering key concepts in the Crime and Punishment topic for WJEC Criminology Unit 4. This resource includes detailed insights into the Criminal Justice System, crime prevention strategies, sentencing models, and the roles of various agencies. Ideal for A-Level revision, ensuring you grasp essential theories and legislative processes to excel in your exams.
1251,6341,024
CriminologyWJEC Unit 4 Criminology
Criminology unit 4 detailed revision note
126,369118
CriminologyCriminology Theories Overview
Explore key criminology theories and their implications on crime and deviance. This comprehensive summary covers biological, psychological, and sociological perspectives, including labelling theory, right realism, and the impact of social campaigns on policy development. Ideal for A-Level criminology students seeking to understand the complexities of criminal behaviour and the factors influencing crime prevention strategies.
129,732211
English LiteratureRomeo and Juliet: Key themes
Key Romeo and Juliet themes and analysed quotes
106,561193
English LiteratureMacbeth: Guilt and Ambition
Explore the complex themes of guilt and ambition in Shakespeare's 'Macbeth'. This analysis covers key characters, including Macbeth and Lady Macbeth, their moral dilemmas, and the tragic consequences of their ambition. Ideal for students studying character motivations, thematic elements, and the psychological impact of power. Includes insights on the natural order, manipulation, and the descent into madness.
918,650387
BiologyAQA Biology: Key Concepts
Explore essential AQA Biology topics including Photosynthesis, Respiration, Homeostasis, Genetics, and Ecology. This comprehensive knowledge organizer covers key concepts such as energy transfer, hormonal control, and genetic variation, providing a solid foundation for your studies. Ideal for exam preparation and understanding biological processes.
108,320295
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user
Chemistry232 views·Updated May 10, 2026·4 pagesGCSE Chemistry Notes: Atmosphere - Topic 9 AQA Overview
The Earth's atmosphere is the gaseous layer surrounding our planet that enables all life. Its composition has changed dramatically over billions of years, from a carbon dioxide-rich environment to the nitrogen-oxygen rich air we breathe today. Understanding these changes helps... Show more
1
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
The Atmosphere's Composition
Our atmosphere today consists mostly of nitrogen (78%) and oxygen (21%), with small amounts of other gases including carbon dioxide, water vapour and noble gases. This composition has remained relatively stable for about 200 million years, but it wasn't always this way.
During Earth's first billion years, intense volcanic activity released gases that formed the early atmosphere, primarily water vapour and carbon dioxide. As the planet cooled, water vapour condensed to form oceans, but carbon dioxide remained dominant in the atmosphere—similar to what we see today on Mars and Venus.
Carbon dioxide levels decreased over time through several natural processes. The gas dissolved in oceans, creating a weak acid that reacted with minerals to form precipitates. These eventually became sediments of carbonate rock on the sea bed. Marine organisms like corals and mussels also used carbon dioxide to create their shells, which later formed limestone when they died.
Did you know? The limestone formations we see today represent carbon dioxide that was once in the atmosphere, showing how Earth naturally sequestered carbon over millions of years!
2
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
The Rise of Oxygen and Fossil Fuels
About 1.7 billion years ago, a major atmospheric shift began when photosynthetic algae evolved in the oceans. These simple organisms produced oxygen as a byproduct of photosynthesis. As plants later evolved on land, oxygen levels continued to increase until they reached a point where animal life could develop.
While oxygen levels rose, carbon dioxide was being trapped in what we now call fossil fuels. Coal formed when plant material in marshy wetlands didn't fully decompose due to lack of oxygen or acidic conditions. Under high pressure and temperature over millions of years, this plant matter transformed into coal.
Crude oil and natural gas formed similarly but from marine organisms. When plankton died and settled in mud on the sea floor, their remains were preserved without decomposition if oxygen was absent. Gradually, heat and pressure transformed these remains—plankton became crude oil, while natural gas (primarily methane) often formed nearby.
Important: The greenhouse effect is actually natural and necessary! Without it, Earth would be too cold for life. Gases like carbon dioxide, water vapour and methane trap the sun's heat by allowing short-wavelength radiation in but absorbing the long-wavelength radiation that the Earth radiates back.
3
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Climate Change and Solutions
Human activities have significantly altered atmospheric composition, particularly through deforestation and fossil fuel use. Cutting down forests not only removes carbon-absorbing trees but also releases stored CO₂. Meanwhile, agriculture—especially cattle farming—produces large amounts of methane, another powerful greenhouse gas.
The impacts of these changes are already visible: melting polar ice, rising sea levels, more severe weather patterns, and shifting distributions of plants, animals and diseases like malaria. While climate models are complex and sometimes lead to simplified predictions, the evidence for human-caused climate change is overwhelming.
Reducing our carbon footprint—the total amount of greenhouse gases produced through our activities—requires both individual and societal changes. Simple steps include better home insulation, using public transport instead of cars, switching to renewable energy sources, and reducing electricity consumption. Eating less beef and dairy also helps reduce methane emissions.
Take action: Calculate your personal carbon footprint online to see which of your daily activities contribute most to greenhouse gas emissions. You might be surprised by what makes the biggest impact!
4
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Air Pollution from Fuels
When we burn fossil fuels like coal and hydrocarbons, they release several harmful pollutants. The carbon and hydrogen in these fuels react with oxygen in the air to produce various compounds, some quite dangerous to human health.
Carbon monoxide is a toxic gas produced by incomplete combustion. It has no colour or smell, making it particularly dangerous—which is why carbon monoxide detectors in homes are so important. When coal containing sulfur is burned, it produces sulfur dioxide, which causes breathing problems and contributes to acid rain.
Vehicles create another set of pollutants. The high temperatures in car engines cause nitrogen and oxygen in the air to react, forming various nitrogen oxides (NOx). These, along with sulfur dioxide, dissolve in rainwater to create acid rain that damages trees and buildings. Cars also release particulates—tiny unburned hydrocarbon particles that increase the risk of heart and lung disease.
Health alert: Air pollution isn't just an environmental issue—it's a major health concern. The World Health Organization estimates that air pollution contributes to millions of premature deaths annually, primarily from respiratory and cardiovascular diseases.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: Atmospheric Chemistry
5ChemistryAQA GCSE Chemistry Revision
Comprehensive revision notes for AQA GCSE Chemistry Paper 2, covering key topics such as organic chemistry, environmental chemistry, chemical reactions, and the structure of DNA. Ideal for higher-tier students preparing for exams, this resource includes essential concepts like hydrocarbons, equilibrium, and sustainable development.
91,72349
ChemistryGreenhouse Gases Overview
Explore the chemistry of the atmosphere with a focus on greenhouse gases, their sources, and effects on climate change. This summary covers key concepts such as the greenhouse effect, carbon dioxide, methane, and the impact of human activities like fossil fuel combustion and deforestation. Ideal for GCSE students studying Topic 9.
93148
ChemistryOrganic Chemistry Insights
Explore key concepts in organic chemistry, including hydrocarbons, chemical reactions, and equilibrium. This mind map covers essential topics for AQA Chemistry Paper 2, such as the properties of hydrocarbons, cracking processes, and the impact of chemical resources on the environment. Ideal for students preparing for exams, this resource provides a clear overview of atmospheric chemistry, rates of reaction, and water resource management.
1149116
ChemistryChemistry of the atmosphere
Triple aqa gcse
11520
ChemistryEarth's Atmospheric Evolution
Explore the formation and evolution of Earth's atmosphere, focusing on volcanic activity, the rise of oxygen through photosynthesis, and the decrease of carbon dioxide. This summary covers key concepts in atmospheric chemistry relevant for GCSE Higher Chemistry students.
112361
Most popular content in Chemistry
9G
ChemistryGCSE AQA Chemistry Topic 1- The Atom
The Atom
109220
Chemistrychem paper 1
higher
111,79137
G
ChemistryGCSE AQA Chemistry Topic 1
Quiz covering all of topic 1
101,6573
ChemistryA-level OCR A Chemistry summary sheets
Everything from snaprevise for OCR chemistry a-level
121,98677
ChemistryEssential Chemistry Practicals
Explore key AQA GCSE Chemistry practicals, including flame tests, titration, and gas identification. This resource covers essential techniques for analyzing ions, making salts, and understanding reaction kinetics. Perfect for students preparing for exams and practical assessments.
1011,774902
C
Chemistrychem paper 1
Unlock the secrets of chemical reactions with this comprehensive flashcard set designed to help you conquer complex concepts and ace your Chemistry exams.
115831
A
ChemistryAQA GCSE Chemistry 4.2 Bonding, structure and the Properties of Matter
4.2 Metals and Alloys
96720
A
ChemistryAQA GCSE Chemistry 4.4 Chemical changes
4.4 Reactions of acids with bases or carbonates
95481
F
ChemistryFundamentals of Atomic Structure
Practice identifying subatomic particles, calculating neutrons, and defining isotopes and atomic/mass numbers.
123380
Most popular content
9SociologySociology of Education Overview
Explore comprehensive A-Level Sociology notes on the education system, covering key theories, policies, and sociological perspectives. This resource includes insights on marketisation, gender roles, cultural deprivation, and educational inequalities, providing a thorough understanding of how education shapes social stratification and individual achievement. Ideal for exam preparation and in-depth study.
12101,9373,035
SociologySociology of Families: Comprehensive Revision
Dive into an extensive overview of family dynamics, perspectives, and patterns in sociology. This resource covers key concepts such as family diversity, gender roles, marriage, and the impact of social policies on family structures. Perfect for A-Level Sociology students preparing for Paper 2.
1271,4942,280
English LiteratureAn Inspector Calls: Character Insights
Explore in-depth analysis and key quotes for characters in J.B. Priestley's 'An Inspector Calls'. This resource covers Gerald Croft, Inspector Goole, Sheila Birling, Mrs. Birling, Eric Birling, and Eva Smith, focusing on themes of class, gender roles, and social responsibility. Ideal for students aiming for Grade 8 and above.
1025,037896
CriminologyCriminology: Crime & Punishment Overview
Comprehensive mindmaps covering key concepts in the Crime and Punishment topic for WJEC Criminology Unit 4. This resource includes detailed insights into the Criminal Justice System, crime prevention strategies, sentencing models, and the roles of various agencies. Ideal for A-Level revision, ensuring you grasp essential theories and legislative processes to excel in your exams.
1251,6341,024
CriminologyWJEC Unit 4 Criminology
Criminology unit 4 detailed revision note
126,369118
CriminologyCriminology Theories Overview
Explore key criminology theories and their implications on crime and deviance. This comprehensive summary covers biological, psychological, and sociological perspectives, including labelling theory, right realism, and the impact of social campaigns on policy development. Ideal for A-Level criminology students seeking to understand the complexities of criminal behaviour and the factors influencing crime prevention strategies.
129,732211
English LiteratureRomeo and Juliet: Key themes
Key Romeo and Juliet themes and analysed quotes
106,561193
English LiteratureMacbeth: Guilt and Ambition
Explore the complex themes of guilt and ambition in Shakespeare's 'Macbeth'. This analysis covers key characters, including Macbeth and Lady Macbeth, their moral dilemmas, and the tragic consequences of their ambition. Ideal for students studying character motivations, thematic elements, and the psychological impact of power. Includes insights on the natural order, manipulation, and the descent into madness.
918,650387
BiologyAQA Biology: Key Concepts
Explore essential AQA Biology topics including Photosynthesis, Respiration, Homeostasis, Genetics, and Ecology. This comprehensive knowledge organizer covers key concepts such as energy transfer, hormonal control, and genetic variation, providing a solid foundation for your studies. Ideal for exam preparation and understanding biological processes.
108,320295
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user