What Fog Visibility represents
For spherical water droplets with extinction efficiency near two, volume-to-area conversion gives extinction about three times liquid water mass divided by twice water density and effective radius. MOR then uses the two-percent contrast constant.
Fog Visibility begins with fog liquid water content, effective droplet radius. Mark each value as observed, remotely sensed, modeled, assumed, or derived, and preserve its valid time and spatial support.
Collecting compatible inputs
Use liquid water content and an area-relevant effective radius from the same fog sample. The page converts grams to kilograms and micrometres to metres.
Record site, coordinates, elevation, timestamp, time zone, path direction, wavelength or sensor band, target definition, cloud-layer method, solar-time convention, averaging period, and quality flags when relevant to Fog Visibility.
Continue the Fog Visibility workflow with the related Solar Elevation Calculator, keeping the same observation support and conventions.
Interpreting Fog MOR estimate
More liquid water shortens range, while larger droplets at fixed water mass reduce total cross-sectional area and lengthen this ideal estimate.
Compare Fog Visibility outputs only after aligning reference height, sky footprint, path, illumination, contrast convention, and temporal average. Similar numbers can describe different optical or geometric quantities.
Boundary and monotonic checks
Liquid water content and effective radius must both be greater than zero.
For Fog Visibility, change one input at a time and predict whether the answer should rise, fall, or remain fixed. Unexpected behavior can expose percent-fraction, degree-radian, metre-kilometre, or layer-order mistakes.
Where the model stops
Real size distributions, wavelength, extinction efficiency, drizzle, multiple scattering, spatial variability, and instrument sampling can strongly change fog visibility.
Fog Visibility is transparent educational arithmetic, not a cloud observation, weather forecast, solar-resource assessment, flight rule, runway visual range report, instrument calibration, or operational safety authority.
Uncertainty and sensitivity
Vary the least certain Fog Visibility input over a credible range and retain the resulting spread in fog mor estimate. Display precision cannot overcome observer classification, retrieval uncertainty, spatial variability, or an empirical coefficient.
A Fog Visibility sensitivity range is not automatically a probability interval. It omits correlations, model-form error, sampling mismatch, sub-grid cloud structure, nonuniform visibility paths, and uncertainty outside the entered variables.
Visibility and contrast conventions
Visibility from Fog Visibility depends on the target contrast threshold and extinction units. Meteorological optical range fixes a two-percent contrast convention; a general contrast range or runway screening estimate may use another threshold.
Do not equate Fog Visibility optical distance with prevailing visibility, slant range, night visual range, or official RVR without the required observation and processing conventions.
Solar geometry and radiation conventions
Solar elevation is measured above the geometric horizon, while azimuth here is clockwise from true north. Fog Visibility must retain whether radiation is normal to the rays or incident on a horizontal surface.
Civil time is not solar hour angle. Longitude, time zone, equation of time, atmospheric refraction, shading horizon, and surface tilt belong in Fog Visibility only when the displayed model explicitly includes them.
Keeping an auditable record
Save raw Fog Visibility inputs, conversions, constants, coefficient sources, formula version, unrounded output, rounded result, and quality flags. A reviewer should reproduce the number without guessing a cover, angle, contrast, or height convention.
If a source value or assumption changes, create a dated Fog Visibility revision. Preserve the earlier output and label whether the change is a correction, a new observation, or a separate scenario.
Formula and convention
The working relationship is MOR = 3.912 ÷ [3LWC ÷ (2ρ_wr)]. Fog Visibility uses only the displayed entries and does not retrieve imagery, station observations, ephemerides, forecasts, or runway systems.
Keep percentages as percentages at entry and convert them to fractions only where the formula shows it. For Fog Visibility, retain angle direction, optical threshold, height reference, and distance unit with the answer.
Continue the Fog Visibility workflow with the related Clear-Sky Solar Radiation Calculator, keeping the same observation support and conventions.
Checked numerical example
At 0.2 g/m³ liquid water and 10 µm effective radius, estimated MOR is approximately 0.1304 km.
Reset restores this Fog Visibility example. Repeat it independently with the stated constants and rounding before replacing demonstration values with observations or scenarios.
Frequent clouds and visibility errors
Typical Fog Visibility errors include mixing oktas and tenths, confusing AGL with MSL, adding overlapping layers, treating degrees as radians, using sea-level-reduced visibility, or applying a two-percent constant to a five-percent threshold.
Reject impossible Fog Visibility combinations rather than forcing an answer. Keep a clear zero distinct from missing or obscured sky, preserve signs on hour angle, and verify every inverse distance and logarithm denominator before downstream use.
Cloud and visibility questions
What does Fog Visibility report?
Fog Visibility reports fog mor estimate from the displayed inputs and formula.
Can forecast or scenario inputs be used?
Yes. Label the Fog Visibility output as a scenario; the page does not fetch or validate a forecast.
How can I verify Fog Visibility?
Repeat MOR = 3.912 ÷ [3LWC ÷ (2ρ_wr)] with the recorded conversions, then test the checked example and a physical boundary.
Why could another source disagree?
Another source may use different cloud overlap, optical threshold, solar convention, coefficient, sensor path, height reference, or rounding than Fog Visibility uses.
Is this an operational visibility or aviation value?
No. Fog Visibility does not replace official weather observations, RVR systems, flight procedures, warnings, or qualified judgment.