Green Flash Refraction Duration Seconds

Convert independently measured spectral refraction separation and apparent solar descent to geometric limb-duration/exposure ratio; no atmospheric dispersion derivation, visible green-flash guarantee or safe-sun viewing advice.

Description

Spectral refraction separates colored solar limb positions.

Spectral refraction separates colored solar limb positions. Dividing an independently measured angular separation by apparent descent rate gives a geometric duration.^[1]

When to use Green Flash Refraction Duration Seconds

Use this tool to convert independently measured spectral refraction separation and apparent solar descent to geometric limb-duration/exposure ratio; no atmospheric dispersion derivation, visible green-flash guarantee or safe-sun viewing advice.

Prepare the observed sounding, cloud records or forecast verification data. Check pressure and height coordinates, wind conventions and the stated units.

How to use Green Flash Refraction Duration Seconds and understand its results

Prepare the observed sounding, cloud records or forecast verification data. Check pressure and height coordinates, wind conventions and the stated units.
Enter greenRedRefractionSeparationArcseconds, observedSolarDescentArcsecondsPerSecond, instrumentExposureSeconds using the field table and calculation rules, then run the tool.
Read geometricSpectralLimbSeparationDurationSeconds, exposureDurationToModelDurationRatio. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
greenRedRefractionSeparationArcseconds	Green red refraction separation arcseconds	number	Required
observedSolarDescentArcsecondsPerSecond	Observed solar descent arcseconds per second	number	Required
instrumentExposureSeconds	Instrument exposure seconds	number	Required

Enter positive solar descent in arcseconds/second, strictly positive green-red separation and nonnegative instrument exposure seconds. Compute separation duration and exposure/duration ratio. Zero separation is rejected because the ratio's duration denominator must be positive.

duration = green-red angular separation/apparent descent rate

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
geometricSpectralLimbSeparationDurationSeconds	Geometric spectral limb separation duration seconds	number
exposureDurationToModelDurationRatio	Exposure duration to model duration ratio	number

json

{
  "input": {
    "greenRedRefractionSeparationArcseconds": 10,
    "observedSolarDescentArcsecondsPerSecond": 5,
    "instrumentExposureSeconds": 1
  },
  "output": {
    "geometricSpectralLimbSeparationDurationSeconds": 2,
    "exposureDurationToModelDurationRatio": 0.5
  }
}

Limitations and assumptions

Atmospheric dispersion is not derived. The result does not guarantee a visible green flash.

Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Rainbow Primary 42 Degree Angle: Compute stationary single internal-reflection spherical-drop rainbow ray under caller wavelength-specific refractive index; not a fixed 42 degree lookup or visible bow forecast. For a complementary task, use Halo 22 Degree Ice Crystal Checker: Compare observed angular radius to ideal 60-degree hexagonal ice-prism minimum deviation under caller index/tolerance; angular agreement does not prove ice crystal habit, visible halo or sun-viewing safety.

References

Green Flash Refraction Duration Seconds — tool.io

Similar or alternative tools

Rainbow Primary 42 Degree Angle
Compute stationary single internal-reflection spherical-drop rainbow ray under caller wavelength-specific refractive index; not a fixed 42 degree lookup or visible bow forecast.
Halo 22 Degree Ice Crystal Checker
Compare observed angular radius to ideal 60-degree hexagonal ice-prism minimum deviation under caller index/tolerance; angular agreement does not prove ice crystal habit, visible halo or sun-viewing safety.