Humidity, Air Velocity and Fog Visibility
Fog visibility is a system outcome. Relative humidity, temperature, air velocity, pressure gradients and camera settings can change the apparent travel distance even when the generator output is unchanged.
Humidity and evaporation
In drier air, fine water droplets can evaporate faster, reducing visible persistence. Higher humidity may extend visibility but can increase local wetting or condensation risk near cold surfaces. Record the environmental conditions instead of treating visual distance as an immutable model specification.
Air velocity and dilution
Faster airflow carries the cloud farther in one sense, but also stretches and dilutes it. Turbulent regions can break the fog into intermittent filaments. A product page distance measured at one humidity and velocity should not be copied into a protocol for a different room without a field check.
Control the comparison
- Use the same hose, outlet and output setting for comparative trials.
- Record temperature, RH and representative air velocity.
- Use the same camera, lens, exposure and lighting.
- Define where “visible distance” ends and who judges it.
- Repeat the trial to separate stable behavior from a transient plume.
Build a defensible fogger requirement
Send Applied Physics the room, process, utilities, documentation and safety constraints—not just a model number.