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  2. Atmosphere of Earth - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Earth

    Composition of Earth's atmosphere by molecular count, excluding water vapor. Lower pie represents trace gases that together compose about 0.0434% of the atmosphere. [5] [6] [7] The three major constituents of Earth's atmosphere are nitrogen, oxygen, and argon. Water vapor accounts for roughly 0.25% of the atmosphere by mass.

  3. Early Earth - Wikipedia

    en.wikipedia.org/wiki/Early_Earth

    Early Earth also known as proto-earth is loosely defined as encompassing Earth in its first one billion years, or gigayear (Ga, 10 9 y), [1] from its initial formation in the young Solar System at about 4.55 Ga to some time in the Archean eon in approximately 3.5 Ga. [2] On the geologic time scale, this comprises all of the Hadean eon, starting ...

  4. Geological history of oxygen - Wikipedia

    en.wikipedia.org/wiki/Geological_history_of_oxygen

    O 2 build-up in the Earth's atmosphere. Red and green lines represent the range of the estimates while time is measured in billions of years ago . Stage 1 (3.85–2.45 Ga): Practically no O 2 in the atmosphere. Stage 2 (2.45–1.85 Ga): O 2 produced, but absorbed in oceans and seabed rock.

  5. Paleoatmosphere - Wikipedia

    en.wikipedia.org/wiki/Paleoatmosphere

    A paleoatmosphere (or palaeoatmosphere) is an atmosphere, particularly that of Earth, at some unspecified time in the geological past.. When regarding geological history of Earth, the paleoatmosphere can be chronologically divided into the Hadean first atmosphere, which resembled the compositions of the solar nebula; the Archean second atmosphere (also known as the prebiotic atmosphere), which ...

  6. File:Atmosphere gas proportions.svg - Wikipedia

    en.wikipedia.org/wiki/File:Atmosphere_gas...

    English: Gas proportions in the Earth's atmosphere. The proportion of water vapor (H₂O) is variable so it is not represented in this chart, however it averages about 1% in the troposphere . Deutsch: Volumenanteil der Gase in der Luft

  7. Paleoproterozoic - Wikipedia

    en.wikipedia.org/wiki/Paleoproterozoic

    The Earth's atmosphere was originally a weakly reducing atmosphere consisting largely of nitrogen, methane, ammonia, carbon dioxide and inert gases, in total comparable to Titan's atmosphere. [6] When oxygenic photosynthesis evolved in cyanobacteria during the Mesoarchean , the increasing amount of byproduct dioxygen began to deplete the ...

  8. Oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Oxygen_cycle

    The Earth's atmosphere, hydrosphere, and biosphere together hold less than 0.05% of the Earth's total mass of oxygen. Besides O 2 , additional oxygen atoms are present in various forms spread throughout the surface reservoirs in the molecules of biomass , H 2 O , CO 2 , HNO 3 , NO , NO 2 , CO , H 2 O 2 , O 3 , SO 2 , H 2 SO 4 , MgO , CaO ...

  9. Archean - Wikipedia

    en.wikipedia.org/wiki/Archean

    Earth's atmosphere at this stage was somewhat comparable to today's atmosphere of Titan. [19] The Archean atmosphere is thought to have almost completely lacked free oxygen; oxygen levels were less than 0.001% of their present atmospheric level, [20] [21] with some analyses suggesting they were as low as 0.00001% of modern levels. [22]