Evolution of the Earth's atmosphere
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Explainer Video
Summary
Evolution of the Earth's atmosphere
In a nutshell
The Earth's atmosphere was formed billions of years ago. The composition of gases in the atmosphere evolved by a decrease in carbon dioxide and an increase in oxygen to form the atmosphere that exists today.
Atmosphere
Definition
The atmosphere is a layer of gases that surrounds a planet.
The two most abundant gases in the Earth's atmosphere are nitrogen and oxygen. Other gases include carbon dioxide, water vapour and the noble gases
Note: Noble gases are the elements in group of the periodic table.
atmospheric gas | PERCENTAGE ABUNDANCE () |
| Nitrogen | |
| Oxygen | |
| Other gases | |
Formation of the Earth's atmosphere
The composition of gases that exist in the atmosphere today are different to the the atmospheric gases formed billions of years ago.
| 1. | Billions of years ago, the Earth was molten and there was no atmosphere. |
| 2. | As the Earth started to cool down, land masses began to form. |
| 3. | Ruptures in the Earth's crust (volcanoes) were formed. |
| 4. | Molten rock, ash and gases erupted from these volcanoes. |
| 5. | The gases which erupted from the volcanoes were: carbon dioxide, hydrogen, nitrogen and methane. |
| 6. | Water vapour condensed to form the oceans, as the Earth began to cool down. |
The gases which erupted from the volcanoes were: carbon dioxide, hydrogen, nitrogen and methane.
Evolution of the Earth's atmosphere
When the Earth's atmosphere was first formed, the percentage abundance of carbon dioxide was high and there was no oxygen. Today, the percentage abundance of carbon dioxide is less than and the percentage abundance of oxygen is , as evolution of the Earth's atmosphere involved the formation of oxygen and increased removal of carbon dioxide from the atmosphere.
Increase of oxygen
Oxygen was formed by photosynthesis. Photosynthesis is the process in which plants and algae convert carbon dioxide and water into glucose and oxygen, using light energy from the sun.
Decrease of carbon dioxide
Plants and algae remove carbon dioxide from the atmosphere by using it up in photosynthesis. The formation of carbonates was another way in which carbon dioxide decreased in the atmosphere.
| 1. | Carbon dioxide dissolved in the oceans, forming carbonic acid. |
| 2. | Carbonic acid released carbonate ions. |
| 3. | Carbonate ions combined with metal ions, forming insoluble compounds. |
| 4. | Marine organisms used up the carbonate compounds to make shells and skeletons. |
FAQs - Frequently Asked Questions
Which gases were released from volcanoes to form the Earth's early atmosphere?
The gases which erupted from volcanoes to form the Earth's early atmosphere were: carbon dioxide, hydrogen, nitrogen and methane.
Which gas is most abundant in the Earth's atmosphere?
Nitrogen is the most abundant gas in the Earth's atmosphere.
What is the atmosphere?
The atmosphere is a layer of gases that surrounds a planet.