AP BIOLOGY

Detailed explanation-1: -To recap, Earth’s early atmosphere was dominated by carbon dioxide and water vapour from volcanoes. As temperatures cooled, the water vapour condensed.

Detailed explanation-2: -Earth’s original atmosphere was probably just hydrogen and helium, because these were the main gases in the dusty, gassy disk around the Sun from which the planets formed. The Earth and its atmosphere were very hot.

Detailed explanation-3: -The Early Atmosphere-Outgassing. Earth’s first atmosphere 4.6 billion years ago was most likely comprised of hydrogen and helium (two most abundant gases found in the universe!) Through the process of outgassing, the outpouring of gases from the earth’s interior, many other gases were injected into the atmosphere.

Detailed explanation-4: -Tiny, ancient meteorites suggest early Earth’s atmosphere was rich in carbon dioxide. Very occasionally, Earth gets bombarded by a large meteorite. But every day, our planet gets pelted by space dust, micrometeorites that collect on Earth’s surface.

Detailed explanation-5: -Most of the planets in our solar system have two or three constituents that make up most of the atmosphere. For example, Venus and Mars have more than 98% of their atmosphere in carbon dioxide and nitrogen, while Earth has 99% of its atmosphere in nitrogen and oxygen.