A tank of recovered water answers a useful question: how much water reached the collector? It does not, by itself, answer how much clearer the air became. The distinction matters because a visibility product is judged by the light that reaches an observer, not the weight of its drainage bottle.
Different measurements weight droplets differently
For spherical droplets, water mass scales with diameter cubed. Their contribution to optical extinction involves cross-sectional area, proportional to diameter squared, multiplied by an extinction efficiency that depends on size, wavelength and refractive index. A few large droplets can therefore carry substantial water while smaller particles contribute materially to the remaining optical obstruction. There is no universal conversion from kilograms collected to metres of visibility restored.
This is especially relevant when hydrated aerosol particles coexist with activated fog droplets. Elias and colleagues measured visible-light extinction associated with hydrated aerosol in mist and fog. More recent Po Valley observations by Neuberger and colleagues show why separating these populations changes the interpretation of particle counts and liquid water. Neither study tests an electrostatic clearing product; both help define what its instruments must see.
Make the optical claim directly
For a uniform optical path, transmission is described by T = exp(−βL), where β is extinction per metre and L is path length. A properly qualified optical measurement can compare this quantity upstream and downstream. Converting it into a visibility distance requires an explicit wavelength, measurement convention and assumption about conditions along the viewing path.
The proposed Weatherhill experiment therefore keeps four records together: direct optical attenuation, the wet particle size distribution, collected water, and temperature, humidity and flow. The spectrum helps explain an optical change; the optical measurement establishes whether that change actually occurred. Missing small particles must be acknowledged and their possible contribution bounded.
A falling particle count in one size bin is also not automatically physical capture. Growth, evaporation or sampling losses can move particles between measured bins. Water collection and a defensible mass balance help distinguish removal from redistribution.
The useful result is consequently specific: a measured reduction in attenuation, under stated fog and flow conditions, relative to a defined comparator. That gives a visibility claim a physical meaning without assuming that water yield already supplies one.