Atmospheric composition and thermal layers
Composition and temperature structure describe different features of Earth's atmosphere.
Key knowledge
Typical lower-atmosphere dry air is approximately 78% nitrogen and 21% oxygen by molecular fraction, with argon and other gases making up most of the remainder; water vapor and aerosols vary. In a representative vertical temperature profile, the troposphere cools upward, the stratosphere warms upward, the mesosphere cools upward and the thermosphere warms upward. Most weather occurs in the troposphere. Stratospheric ozone absorbs solar ultraviolet energy. The rarefied exosphere is a transition toward space, rather than a solid outer boundary.
Conditions and scope
- The dry-air percentages are approximate lower-atmosphere composition, not a fixed water-vapor fraction or the mixture at every altitude.
- Layer heights and profiles vary with latitude, season and state; local temperature inversions occur. High thermospheric temperature does not imply a dense, strongly heating gas.
Sources · 4
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
UCAR Center for Science Education2 sources
- Layers of the atmosphereNational Oceanic and Atmospheric Administration, JetStreamTeaching resource
- Earth’s atmosphereMet OfficeTextbook chapter
Evidence and review
Approximate dry lower-air composition and the representative vertical thermal layers, with ultraviolet heating and variable boundaries.
2026-10-10 · Independent Mathematics and Information editor (AI editorial/source review; not the Chemistry/Biology/Earth author). The specified introductory inventory has no unresolved demonstrated material gap after the changes and body-based reuse. Existing advanced references retain their historical scoped approvals. English-only reference prose and explicit Lithuanian-translation-pending status are preserved.
Foundational review
2026-10-10 · Independent AI editorial inspection of this new compact reference entry, its equations, applicability, sources and knowledge connections.
Sources from other places
Agreement within this scope
Approximate major gas fractions and representative temperature-defined layers.
Water content, layer heights and local temperature profiles vary.
Met Office
- Earth’s atmosphere United KingdomEnglish
Earth’s atmosphere composition; Earth’s atmosphere layers
- Earth’s atmosphere
Entry details
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- foundation-earth-atmosphere-layers
- Revision
- foundations-audit.1
- Structured reference record
- Foundational core completion