Wildfire Knowledge Graph · Smoke & Indoor Air
Dilution and spreading of smoke through atmospheric mixing, turbulence and changing transport conditions.
In plain language
Dilution and spreading of smoke through atmospheric mixing, turbulence and changing transport conditions.
Why it matters
Smoke Dispersion is useful because it separates one specific part of wildfire behaviour, exposure, operations or evidence from nearby concepts that can otherwise be mixed together.
What is smoke dispersion?
Smoke dispersion is the atmospheric transport, dilution and redistribution of smoke after fire emissions enter the atmosphere.
Two processes occur together: transport moves smoke horizontally and vertically, while dispersion mixes it through a larger volume of air.
Smoke dispersion is not PM2.5
- Smoke dispersion: atmospheric transport and dilution process.
- PM2.5: particle concentration at a place and time.
- AQI: a public-health reporting scale derived from pollutant concentration.
- Smoke plume: the visible or modeled body of smoke produced by the fire.
Strong dispersion close to a fire can still transport smoke rapidly toward a downwind community. “Good dispersion” does not mean the smoke disappears.
Core atmospheric chain
Atmospheric Stability → Mixing Height → Transport Wind → Ventilation Rate → Smoke Dispersion → Downwind Concentration
Operational relationship
A widely used fire-weather screening quantity is:
Ventilation Rate = Mixing Height × Transport Wind
For example, 4,000 ft × 15 kt = 60,000 knot-ft. Under one commonly used National Weather Service profile, that enters the “Good” category. Category thresholds are operational conventions and are not universal.
What controls smoke dispersion?
- Mixing height and boundary-layer depth.
- Transport-wind speed and direction.
- Atmospheric stability and temperature inversions.
- Terrain, valleys and drainage flows.
- Plume buoyancy and injection height.
- Time of day and boundary-layer evolution.
- Emission rate and duration.
Evidence and reconstruction
For incident analysis, preserve the forecast issue time, observed weather, mixing-height estimate, transport wind, plume or satellite observations, PM2.5 measurements and receptor location. A forecast and a later reanalysis should remain separate evidence objects.
Interpretation checklist
- Distinguish forecast from observation.
- Preserve units, source and timestamp.
- Use the issuing agency’s category definitions.
- Do not infer PM2.5 concentration from ventilation rate alone.
- Consider terrain, inversions and vertical plume structure.
Related concepts
Fire Weather · Atmospheric Stability · Mixing Height · Transport Wind · Ventilation Rate · Smoke Plume · Smoke & Indoor Air Quality
Technical references
National Weather Service — Smoke Dispersal and Ventilation Rate
National Weather Service — Fire Weather Definitions
Tecnobosque Reference Concept · reviewed September 2026. Forecast conventions and ventilation categories should be interpreted using the issuing agency’s current definitions.