The gaseous and particulate makeup of the atmosphere — major gases, trace gases, aerosols, and their spatial distribution. This is the background chemistry of the air, distinct from pollutant concentrations which are Atmosphere Contaminants.
Scope
- Major atmospheric gases: N₂, O₂, Ar, CO₂ (as background composition)
- Trace gases: Water vapour profiles, ozone column, methane background levels
- Aerosols: Natural aerosol loading (dust, sea salt, volcanic), aerosol optical depth
- Atmospheric profiles: Vertical soundings, radiosonde data, lidar profiles
Distinction from Contaminants
The boundary between composition and contaminants is contextual. Background CO₂ levels as an atmospheric property = composition. Elevated CO₂ from industrial emission = contaminant. If the focus is “what’s in the air naturally?”, it’s composition. If the focus is “what pollutants are present?”, it’s contaminants.
Classical Theme Mappings
| Standard | Theme | Link |
|---|---|---|
| ISO 19115 | Climatology/Meteorology/Atmosphere | Atmosphere |