The Atmsphere Flashcards
Why do scientists study the atmospheres of other bodies in our Solar System?
Scientists study these atmospheres to investigate the Earth’s atmosphere before life evolved, as these bodies are unlikely to contain life and may have atmospheres similar to the Earth’s early atmosphere.
What was the composition of the Earth’s early atmosphere?
The Earth’s early atmosphere is thought to have been mainly carbon dioxide, with smaller amounts of water vapour and other gases, and little or no oxygen.
How do volcanoes affect the atmospheres of planets?
Volcanoes release large amounts of gases such as carbon dioxide and water vapour, and small amounts of other gases including nitrogen.
What gas is most likely to have formed most of the Earth’s early atmosphere?
Carbon dioxide.
Why does the discovery of Titan’s icy interior not support the idea that the Earth’s early atmosphere was mainly nitrogen?
Titan has an icy interior, unlike Earth, Venus, or Mars, suggesting that Earth’s early atmosphere is less likely to have been like Titan’s.
Why do scientists think that the early Earth had an atmosphere similar to Venus?
Earth, Venus, and Mars are rocky planets with volcanoes, and the atmospheres of Venus and Mars are mainly made of carbon dioxide, supporting the idea that Earth’s early atmosphere also contained lots of carbon dioxide.
How may the Earth’s oceans have formed?
The Earth’s oceans may have formed when water vapour in the atmosphere condensed to liquid water.
What evidence supports the idea that oxygen was not present in the early Earth’s atmosphere?
Oxygen is not produced by volcanoes, and iron pyrite, which only forms if there is no oxygen, is often found in very ancient rock.
Why are scientists more certain about the oxygen content of the early atmosphere compared to other gases?
Scientists have more direct evidence regarding the presence of oxygen, such as the oxidation of iron and fossil evidence of microorganisms that may have produced oxygen.
How did the Earth’s cooling 4 billion years ago cause a change in the composition of the atmosphere?
The cooling caused water vapour in the atmosphere to condense to liquid water, forming the oceans.
What evidence suggests that the composition of the Earth’s early atmosphere was mainly carbon dioxide?
Evidence includes the volcanic activity that released large amounts of carbon dioxide and the similarities with the atmospheres of Venus and Mars.
Why do many scientists think that the Earth’s early atmosphere was similar to that of Mars today?
Mars today has an atmosphere that is 95.3% carbon dioxide, which is similar to what scientists believe the Earth’s early atmosphere contained.
