Planetary atmospheres depend fundamentally upon their geochemical inventory, temperature and the ability of their gravitational field to retain gases. In the case of Earth and other inner planets, early outgassing released mainly carbon dioxide and water vapour. The secondary veneer of comets and meteorites added further volatiles. Photodissociation caused secondary changes, including the production of traces of oxygen from water. Earth's gravity cannot retain light gases, including hydrogen. but retains oxygen. Water vapour generally does not pass the cold trap at the stratopause. In the archaean, early evolution of life, probably in hydrothermal vents, and the subsequent development of photosynthesis in surface waters, produced oxygen, at 3500 Ma or even earlier, becoming a significant component of the atmosphere from about 2000 Ma. Thereafter banded iron formations became rare, and iron was deposited in oxidized red beds. Atmospheric levels of carbon dioxide and oxygen have varied during the Phanerozoic: major changes may have caused extinctions. particularly the Permian/Triassic. The declining greenhouse effect due to the long-term decrease in carbon dioxide has largely offset increasing solar luminosity, and changes in carbon dioxide levels relate strongly to cycles of glaciation.

中文翻译：

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气氛的演变。

行星大气从根本上取决于其地球化学物质，温度以及其重力场保持气体的能力。就地球和其他内部行星而言，早期除气主要释放出二氧化碳和水蒸气。彗星和陨石的次要表面饰板进一步增加了挥发物。光解离引起二次变化，包括从水中产生痕量的氧气。地球的重力无法保留包括氢在内的轻质气体。但保留氧气。水蒸气通常不会通过平层顶上的冷阱。在古细菌中，生命的早期进化，可能是在热液喷口中，以及随后在地表水中光合作用的发展，在3500 Ma或更早的时间就产生了氧气，从2000 Ma左右开始成为大气的重要组成部分。此后，带状铁的形成变得罕见，铁沉积在氧化的红层中。在生代时期，大气中的二氧化碳和氧气含量发生了变化：重大变化可能导致了灭绝。特别是二叠纪/三叠纪。由于二氧化碳的长期减少而导致的温室效应的下降在很大程度上抵消了日光亮度的提高，二氧化碳水平的变化与冰川周期密切相关。