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Short answer

The atmosphere is a layer of gas held to Earth by gravity, thinning with height. Scientists divide it into five layers by how temperature, chemistry and density change: troposphere, stratosphere, mesosphere, thermosphere and exosphere. Nitrogen is by far its most common gas. [S1][S2]

Key points

• The stratosphere runs from about 4-12 miles up to about 31 miles and holds 19 percent of the atmosphere's gases. [S2]
• Meteors burn up in the mesosphere. [S2]
• The exosphere, the outermost layer, reaches up to about 6,200 miles; atoms escape to space there. [S2]

Claims

• id: C1 claim: Nitrogen is by far the most common gas in dry air. source: S1 evidence: "nitrogen by far is the most common"
• id: C2 claim: The top four gases make up 99.998% of the atmosphere. source: S1 evidence: "with the top four making up 99.998% of all gases"
• id: C3 claim: Five distinct layers have been identified. source: S2 evidence: "Five distinct layers have been identified"
• id: C4 claim: The stratosphere holds 19 percent of the atmosphere's gases. source: S2 evidence: "This layer holds 19 percent of the atmosphere's gases"

Sources

• [S1] The Atmosphere. NOAA. https://www.noaa.gov/jetstream/atmosphere . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Layers of the Atmosphere. NOAA. https://www.noaa.gov/jetstream/atmosphere/layers-of-atmosphere . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_2h56y8zc,
  author = {{iinventedlight}},
  title = {{The layers of Earth's atmosphere}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/atmosphere-layers/},
  note = {Permanent ID iil:note:2h56y8zc. License: CC-BY-4.0.},
}

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