Grade 9 ↓
Air and atmosphere
Air is a fundamental component of Earth's environment. It is the invisible gaseous substance that surrounds Earth, a mixture of primarily nitrogen and oxygen. The atmosphere is a layer of gases that surrounds our planet, held in place by Earth's gravity. It is vital to the existence of life because it provides gases necessary for breathing, acts as a shield protecting us from harmful solar radiation, and plays an important role in weather patterns and climate conditions.
Composition of air
Air is made up of many different gases. The two most common gases in air are nitrogen and oxygen. Here is a description of the composition of air by volume:
- Nitrogen: 78% - Oxygen: 21% - Argon: 0.93% - Carbon dioxide: 0.04% - Other gases: trace amounts
Visual example of air composition
The role of nitrogen in the air
Nitrogen is the most abundant gas in Earth's atmosphere. It plays a vital role in the nitrogen cycle, which helps maintain ecosystem health. Nitrogen is essential for all living organisms because it is a building block of amino acids, proteins, and nucleic acids.
The role of oxygen in the air
Oxygen is vital for the survival of aerobic organisms. It is used in cellular respiration, where it helps convert food into energy. Green plants and algae also produce oxygen during photosynthesis, a process that uses carbon dioxide, water, and light energy to produce glucose and oxygen.
Argon and other noble gases
Although argon and other noble gases such as krypton and xenon are present only in trace amounts, they also play important roles. Argon is used in fluorescent lighting and welding. These gases are chemically inert and contribute to the stability of air.
Carbon dioxide in the air
Carbon dioxide is a greenhouse gas that plays a key role in regulating the Earth's temperature. Plants use it to make energy-rich glucose during photosynthesis. Human activities such as burning fossil fuels have increased CO2 levels in the atmosphere, contributing to global warming.
Visual example of carbon dioxide regulation
Physical properties of air
Air has several physical properties:
- It is colorless and odorless.
- Air can expand and contract with changes in temperature.
- Air exerts pressure; the weight of the atmosphere pressing down on the Earth's surface is known as atmospheric pressure.
Layers of the atmosphere
The Earth's atmosphere is made up of several layers, each of which has its own characteristics. These layers include:
- Troposphere: The lowest layer of the atmosphere, extending about 8-15 kilometers above the Earth's surface. This is where most of our weather occurs. The air is densest in this layer.
- Stratosphere: Above the troposphere, extending from about 15 to 50 kilometers. This layer contains the ozone layer, which absorbs and scatters ultraviolet solar radiation.
- Mesosphere: Extends from 50 to 85 kilometers. This is the layer where most meteors burn up as they enter.
- Thermosphere: Extends from 85 to 600 km. Aurora occurs in this layer. The temperature is very high due to the absorption of high energy radiation.
- Exosphere: The outermost layer, extending from 600 km to 10,000 km. It gradually disappears into outer space.
Visual example of atmospheric layers
Functions of the atmosphere
The atmosphere plays the following important roles:
- Protection: The atmosphere protects life on Earth by blocking harmful solar radiation and moderating temperature extremes between day and night.
- Supportive to life: Provides essential gases such as oxygen and carbon dioxide for respiration and photosynthesis.
- Climate and weather regulation: The atmosphere helps distribute heat around the globe and causes weather phenomena.
- Pressure and buoyancy: Air pressure helps in processes like wind and precipitation by creating buoyancy.
Importance of the ozone layer
The ozone layer is located in the stratosphere and consists of ozone (O3) molecules. It plays a vital role in protecting the Earth from harmful ultraviolet (UV) radiation. UV radiation can cause skin cancer, cataracts, and other health problems in humans and animals. Additionally, it can also affect plant growth and marine ecosystems.
Human impact on the atmosphere
Human activities have had a significant impact on the atmosphere. These impacts include:
- Air pollution: Emissions of pollutants such as carbon monoxide, sulphur dioxide and nitrogen oxides from vehicles and industries, causing smog and health problems.
- Ozone layer depletion: Emissions of chlorofluorocarbons (CFCs) damage the ozone layer, increasing UV radiation.
- Global warming: Increasing amounts of greenhouse gases such as CO2 trap more heat in the atmosphere, leading to climate change.
Lesson example of human impact on air
Consider the increasing use of fossil fuels since the Industrial Revolution. These activities have increased CO2 levels from about 280 ppm (parts per million) to more than 400 ppm today.
Preserving atmospheric health
It is important to take steps to preserve and protect the health of our atmosphere. These measures include:
- Reducing emissions from industries and vehicles.
- Promoting alternative energy sources like solar and wind.
- Protect forests and promote afforestation to enhance CO2 absorption.
- Enforcing regulation on pollutant emissions.
Conclusion
Understanding air and the atmosphere is vital to understanding their role in sustaining life and the environment. These components interact in complex ways and affect weather, climate, and life on Earth. The protection and preservation of the atmosphere is essential to the continued existence and well-being of life on our planet.