---
source: https://iinventedlight.com/library/notes/atmosphere-layers.md
title: "The layers of Earth's atmosphere"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA, The Atmosphere, US government work, public domain; NOAA, Layers of the Atmosphere, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "science-explain: weather and atmosphere"
tags: science, atmosphere, earth
sources:
  - id: S1
    title: "The Atmosphere"
    publisher: NOAA
    url: https://www.noaa.gov/jetstream/atmosphere
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "Layers of the Atmosphere"
    publisher: NOAA
    url: https://www.noaa.gov/jetstream/atmosphere/layers-of-atmosphere
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# The layers of Earth's atmosphere

## 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).