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Visibility, Extinction and 5% Optical Range

Calculate contrast-limited range and 5% meteorological optical range from extinction or transmission, retaining the optical measurement basis.

Use this result well

Inputs that matter
Extinction coefficient (km⁻¹), Contrast fraction, Sources and assumptions, Optical baseline (m), and 1 more
Output to expect
Extinction and contrast range, MOR from measured transmission
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Extinction and contrast range

Calculate homogeneous-path contrast range from extinction and a contrast fraction. The 5% meteorological optical range is reported separately; a 2% threshold must not be mislabeled as the 5% MOR definition.

Range = −ln(contrast fraction)/σ; MOR = −ln(0.05)/σ.

MOR from measured transmission

Infer homogeneous-path extinction and 5% MOR from a documented optical baseline and transmission fraction. Unit transmission has zero inferred extinction and no finite attenuation-limited MOR.

σ = −ln(transmission)/baseline; MOR = −ln(0.05)/σ.

Updated: September 2026

Example Scenarios

Inspect the example and its input basis, then substitute your own documented measurements or matched cases.

Extinction coefficient (km⁻¹): 0.5Contrast fraction: 0.05

→ 5.991465 km contrast-limited range

Inspect the example and its input basis, then substitute your own documented measurements or matched cases.

Optical baseline (m): 100Transmission fraction: 0.9

→ 2.843316 km meteorological optical range

Common Mistakes to Avoid

Mixing observation and model inputs

Use the exact units, timestamp, level and measurement or model basis stated by the selected mode. A similar quantity from another instrument or product is not automatically interchangeable.

Treating an illustrative case as a measurement

Replace the example with your own sourced inputs. Retain missing values and method limits, and keep raw source data alongside a saved calculation.

FAQ

Calculate homogeneous-path contrast range from extinction and a contrast fraction. The 5% meteorological optical range is reported separately; a 2% threshold must not be mislabeled as the 5% MOR definition. Infer homogeneous-path extinction and 5% MOR from a documented optical baseline and transmission fraction. Unit transmission has zero inferred extinction and no finite attenuation-limited MOR.

Retain the station or profile identity, observation or issue/valid time, measurement units, quality flags, source and stated method. Missing values, trace precipitation and known zeros have different meanings.

Save weather case keeps an explicit local record. Copy MD includes current inputs and notes; Download CSV includes the current result breakdown. Keep portable copies separately and retain raw source data.

About Visibility, Extinction and 5% Optical Range

Calculate homogeneous-path contrast range from extinction and a contrast fraction. The 5% meteorological optical range is reported separately; a 2% threshold must not be mislabeled as the 5% MOR definition. Infer homogeneous-path extinction and 5% MOR from a documented optical baseline and transmission fraction. Unit transmission has zero inferred extinction and no finite attenuation-limited MOR.