What Cloud Solar Attenuation represents
This simple model removes a selected fraction of clear-sky irradiance in proportion to cloud cover. The coefficient is the assumed loss at complete cover.
Cloud Solar Attenuation begins with clear-sky irradiance, cloud cover, attenuation coefficient. Mark each value as observed, remotely sensed, modeled, assumed, or derived, and preserve its valid time and spatial support.
Visibility and contrast conventions
Visibility from Cloud Solar Attenuation 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 Cloud Solar Attenuation 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. Cloud Solar Attenuation 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 Cloud Solar Attenuation only when the displayed model explicitly includes them.
Continue the Cloud Solar Attenuation workflow with the related Runway Visual Range Estimate Calculator, keeping the same observation support and conventions.
Keeping an auditable record
Save raw Cloud Solar Attenuation 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 Cloud Solar Attenuation 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 G = G_clear[1 − a(C/100)]. Cloud Solar Attenuation 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 Cloud Solar Attenuation, retain angle direction, optical threshold, height reference, and distance unit with the answer.
Checked numerical example
At 800 W/m², 60% cover, and coefficient 0.7, the attenuated value is exactly 464 W/m².
Reset restores this Cloud Solar Attenuation example. Repeat it independently with the stated constants and rounding before replacing demonstration values with observations or scenarios.
Continue the Cloud Solar Attenuation workflow with the related Extraterrestrial Solar Radiation Calculator, keeping the same observation support and conventions.
Continue the Cloud Solar Attenuation workflow with the related Cloud Base Height Calculator, keeping the same observation support and conventions.
Collecting compatible inputs
Use clear-sky irradiance for the same surface, solar geometry, and interval. Choose the coefficient from a documented calibration or label it explicitly as a scenario.
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 Cloud Solar Attenuation.
Interpreting Cloud-attenuated irradiance
Higher cover or coefficient lowers the output linearly. The result is broadband irradiance under the selected assumption, not cloud optical depth.
Compare Cloud Solar Attenuation 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
Zero cover or zero coefficient preserves clear-sky irradiance; full cover leaves the fraction one minus the coefficient.
For Cloud Solar Attenuation, 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
Cloud type, thickness, multilayer overlap, sun position, reflection, broken-cloud enhancement, surface albedo, and diffuse radiation make real response nonlinear.
Cloud Solar Attenuation 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.
Continue the Cloud Solar Attenuation workflow with the related Meteorological Optical Range Calculator, keeping the same observation support and conventions.
Uncertainty and sensitivity
Vary the least certain Cloud Solar Attenuation input over a credible range and retain the resulting spread in cloud-attenuated irradiance. Display precision cannot overcome observer classification, retrieval uncertainty, spatial variability, or an empirical coefficient.
A Cloud Solar Attenuation 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.
Cloud amount, overlap, and layers
Cloud fraction is an area or sky-dome proportion, while a ceiling is a height classification and optical depth is attenuation. Cloud Solar Attenuation should not substitute one quantity for another merely because each relates to cloud.
When layers enter Cloud Solar Attenuation, state whether overlap is random, maximum, observed, or ignored. Adding layer percentages directly can exceed 100% and double-count vertically aligned cloud.
Frequent clouds and visibility errors
Typical Cloud Solar Attenuation 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 Cloud Solar Attenuation 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.
Questions about the sky model
Is this an operational visibility or aviation value?
No. Cloud Solar Attenuation does not replace official weather observations, RVR systems, flight procedures, warnings, or qualified judgment.
How should the result be rounded?
Keep full precision inside Cloud Solar Attenuation, then round no more finely than the least certain measurement or model assumption supports.
When should I recalculate?
Recalculate Cloud Solar Attenuation when its site, time, path, layer, sky footprint, illumination, source observation, or model assumption changes.
What does Cloud Solar Attenuation report?
Cloud Solar Attenuation reports cloud-attenuated irradiance from the displayed inputs and formula.
Can forecast or scenario inputs be used?
Yes. Label the Cloud Solar Attenuation output as a scenario; the page does not fetch or validate a forecast.
How can I verify Cloud Solar Attenuation?
Repeat G = G_clear[1 − a(C/100)] 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 Cloud Solar Attenuation uses.