Applying voltage is an actuator setting, not a weather outcome. Between the power supply and an optical result lie ion production, transport, droplet charging, particle interactions and airflow. Changing one setting can alter several of these processes at once. A useful controller therefore needs observations of the target response, rather than an assumption that a larger electrical input is always better.
In Reading’s natural-fog charge-injection experiment, one negative-charge condition increased measured mass concentration in the 1 μm channel by 95.3%. This was a result for one part of the measured size distribution. It was not a 95.3% increase in rainfall, and it did not demonstrate an equivalent improvement in visibility.
A separate drone charge-emission experiment examined local optical changes in natural fog. The aircraft experiment found different radiative responses for unipolar and bipolar emission, with a smaller response when both emitters operated. This was not a calibrated visibility-restoration measurement, and it does not supply a universal operating curve for a collector or an operational fog-clearing service.
Treat the shape of the response as a question
Electrical attraction, repulsion and induced charge distributions can affect particle encounters differently. Residence time, droplet size and the surrounding field also matter. A charged population can change its size distribution without leaving the air. Consequently, an electrical response should not be equated with capture, and capture should not be equated automatically with the desired optical outcome.
The proposed Weatherhill discovery stage treats the response as potentially nonmonotonic. That is a design precaution, not a claim that every fog system has an established rise-and-fall curve. It calls for testing a bounded set of settings, retaining adverse responses, and choosing a candidate with a predeclared rule.
Measure delivered conditions near the target as well as settings at the source. An electrode voltage, ion counter or field mill alone does not specify the charge carried by every droplet size. Record flow, humidity, electrical behaviour, direct attenuation and wet particle spectra together, with an appropriate time alignment.
Bipolar operation can be an exploratory condition when the apparatus supports it. A null result would apply to that exposure and its measurement sensitivity; it would not prove that all bipolar approaches are ineffective. The eventual controller must also be able to back off or remain off when the measured benefit disappears.