Build the measurement.
Then test the collector.

The first useful result is a trustworthy measurement.

FogLab will compare a powered collector with the same physical collector unpowered. The main question is whether electrical operation reduces optical extinction beyond passive capture under specified fog and flow conditions. Recovered water, wet-particle size, charge, pressure loss and energy help explain that result.

We are developing the apparatus in-house. Suppliers and specialists can contribute components, calibration, design review and independent observation. An external host laboratory is not a prerequisite. Clearing a road, port or runway remains a separate scale-up question.

This document is a design addendum and quotation brief, not a replacement preregistration. WX-FOG-001 v0.2 remains the published experimental proposal. Departures affecting its population, comparison or analysis must be documented and resolved before the data they govern are collected. [1]

Follow the air. Record what changes.

The diagram separates aerosol conditioning, treatment and measurement. It describes functional interfaces; flow conditioning, sampling positions, optical paths and ventilation remain design choices.

These values follow Q = area × velocity and transit time = length ÷ velocity. Actual throughput depends on resistance, leakage and velocity profile. Separate collected water from wall deposition.

A conditioned, once-through reach preserves the intended exposure. Recirculation can alter the incoming size distribution and charge, even at constant extinction. It requires qualified recovery and a prospectively defined exposure and unaffected reference; the unchanged normalized endpoint cannot simply be assumed. [1]

Choose the path from the signal we need.

Measure transmission and extinction directly at a specified wavelength and receiver geometry. Any derived visibility must state its contrast convention and homogeneity assumption. A 20% decrease in extinction implies a 25% increase in equivalent visibility, under the same convention.

Independent Beer–Lambert calculations. At fixed numerical visibility, the conventions imply different extinction. WMO meteorological optical range uses a 5% photometric transmission definition; a narrowband test does not automatically qualify that measurement. [11]

At 100 m equivalent visibility, the 0.3 m path produces only a 0.1783-point signal under the 5% convention. If two normalized readings each had independent 0.2-point standard uncertainty, their difference would have approximately 0.283-point uncertainty. “0.2% stability” is therefore incomplete without its definition, averaging time, comparison channels and uncertainty propagation. [4]

Budget reference noise, dark signal, linearity, alignment, contamination, drift and covariance against a minimum useful extinction change. Denser mist helps commission the readout but also changes the collector experiment.

Neither arrangement earns validity through length alone. Forward-scattered light accepted by a receiver can bias inferred extinction. Electrical operation can also change deposition on optical surfaces. Include clean-flow, aerosol and electrically switched blank checks, with a defensible sampled volume. [5]

Make a population we can describe.

Salt-containing aerosol is a practical development route because composition and humidity can be controlled. Record the seed recipe, water quality, temperature, relative humidity and wet-size distribution. An optical density alone does not identify droplet size, liquid water or electrostatic response.

Sandia’s 2015 account describes sodium-chloride solution sprayed above 95% relative humidity, initial wet droplets around 2.3 times their dry diameter, and useful density persistence up to 30 minutes. Those are reported chamber conditions, not a universal growth factor, exact median size or numerical stability tolerance. [2]

The 2017 technical manuscript is more specific about limits: its generated particles were smaller than the compared natural-fog models and resembled some light radiation fogs or heavy mists. Its 25 L/min sampling flow belonged to an instrument inlet, not the chamber throughput. A largely static chamber does not qualify our 1–4 m/s through-flow conditions. [3]

Initial optical commissioning can precede complete sizing. Full protocol discovery and selected-setting testing need the characterized, frozen wet population and qualified size range called for in v0.2. Incomplete spectral evidence does not automatically invalidate a sound direct optical observation; it limits mechanism, closure and transfer claims. Spectrum-derived extinction needs appropriate optical modeling rather than a universal extinction-efficiency assumption. [1]

Commission. Qualify. Compare.

Each gate produces a reviewable record. Keep qualification, exploratory work, fresh pilot and independent confirmation days separate in the schedule, budget and dataset. [1]

Powered-fog outcomes used to choose hardware are efficacy search. Before collecting them, define a separate preliminary feasibility protocol or prospectively revise the frozen 60-comparison allocation. This brief approves neither change; such data stay outside the fresh variance pilot and confirmation. [1]

The four runs in a confirmation day require 28 minutes of baseline plus primary acquisition, before settling and resets. Sandia’s typical 10–20-minute tests do not qualify that schedule. Independent days also require the prescribed preparation and calibration checks. [1] [2]

Use the sample-size planner with the selected-setting pilot. Its confirmation count excludes qualification, discovery, pilot work, resets and failed runs.

Quote functions, interfaces and acceptance.

Quote assumptions, exclusions, lead times, commissioning and evidence for performance specifications. Include geometry explicitly: USDA’s nozzle studies show that charge delivery changes with electrode gap and operating conditions. [9]

Separate hardware from engineering labor, workspace, installation, calibration, consumables, metrology access and experimental days. A limited apparatus allowance cannot be read as the complete protocol budget. Renting an instrument may reduce initial purchase cost while leaving qualification and integration work intact.

As a dated scale reference, a UV-106-L ozone analyzer was publicly listed at US$5,925 on 11 October 2026. That is one instrument’s advertised price, not our quoted cost or a selected model. The offered revision, sampling accessories, calibration, taxes, shipping and alarm integration require an actual quote. [8]

Design the wet system as one system.

The workspace review covers electrical isolation, enclosure, interlocks, drainage, condensation, corrosion, stored energy, service access and exhaust. An electrical specialist should define and verify protective functions.

For any corona-based option, specify ozone monitoring and gas removal separately from droplet or particulate filtration. OSHA’s ozone limit is a 0.1 ppm eight-hour time-weighted average; NIOSH separately recommends a 0.1 ppm ceiling. Neither is a universal instant-shutdown setpoint. A qualified exposure review must define the local controls, monitoring locations and response rules. [6] [7]

Room-air protection and wet-duct process sampling are different placements. The analyzer’s current manufacturer manual warns against inlet pressurization and corrosive by-products from air-fed ozone generation. Obtain vendor acceptance of the proposed humid-corona sampling arrangement; untreated fog is not a qualified inlet. Validate conditioning losses, delay and calibration. [10]

Keep protective control independent of the browser. Verify fault handling before energized wet testing and record configuration changes.

Resolve these before freezing the build.

1. Optical objective. What extinction change matters, in which fog population, over which averaging and comparison interval?
2. Geometry. Which path arrangement, sampled volume and flow-conditioning length satisfy that uncertainty budget?
3. Population. What wet-size range, seed composition and humidity conditions are qualified, and where are the remaining measurement gaps?
4. Actuator. Which collector design and controlled electrical conditions can be compared without changing passive geometry?
5. Operations. Which workspace, protective systems, calibration route and named review responsibilities support the experiment?
6. Cost and schedule. What do actual quotes include, and what remains outside the apparatus allowance?

The build handover should contain drawings and interfaces, configuration inventory, calibration evidence, qualification data, operating limits, raw-data schema and an acceptance record. The experimental release then adds the frozen analysis, allocation schedule, pilot-derived sample size and a dated account of departures from the published proposal.

What each source supports.

Sources checked on 11 October 2026. Calculations and proposed acceptance requirements are Weatherhill design work. Source inclusion does not imply endorsement, a supplier appointment or a partner agreement.

1. WX-FOG-001 v0.2 — published protocolExperimental sequence, characterization requirements and analysis commitments; unchanged by this build brief.
2. Sandia — controlled fog chamber, 17 June 2015A historical facility account of salt-containing aerosol, humidity and useful test windows; no numerical stability guarantee.
3. Wright and colleagues — optical characterization, SAND2017-4910CFull technical manuscript: generated size spectrum, sampling method and limits of similarity to natural fog.
4. NIST — combining uncertainty componentsPropagation of measurement uncertainty, including covariance; used for the signal-budget examples.
5. Hutt — forward scattering in atmospheric transmission measurementsPrimary experimental abstract on receiver geometry and the bias from accepted scattered light.
6. OSHA — ozone exposure limitsThe federal 0.1 ppm permissible exposure limit is an eight-hour time-weighted average.
7. NIOSH — ozone pocket guideSeparately identifies a recommended 0.1 ppm ceiling; these quantities do not define an apparatus trip setting.
8. Oxidation Technologies — UV-106-L listingAdvertised price checked on 11 October 2026; not a quotation or a selected instrument.
9. USDA ARS — electrostatic nozzle-gap experimentsEvidence that geometry and operating conditions affect spray charging; not a fog-clearing performance claim.
10. 2B Technologies — Model 106-L manual, Rev. K-1Manufacturer requirements for sampling, inlet pressure, corrosive by-products and calibration; March 2025 revision.
11. WMO OSCAR — meteorological optical rangeThe 5% luminous-transmission definition and its photometric measurement convention.