Sun Dog Parhelia Offset Angle Calculator
Minimum-deviation geometric offset through a 60-degree ice prism, ideal horizontal ray branch; not a full solar-altitude parhelion model.
Description
Sun Dog Parhelia Offset Angle Calculator: return minimum deviation degrees.
A prism's minimum deviation angle depends on its apex angle and refractive index. A simple 60-degree prism model provides an optical reference.
This tool returns minimum deviation degrees. Use the stated units and model convention when interpreting these fields.
When to use this tool
Use this tool when the supplied inputs match the specific operation described above and you need a repeatable result under its stated convention.
- Check the supported input and output contract against an existing calculation or observation.
- Use the complete example to confirm units, selector spelling and result interpretation.
How to use the tool and how it works
- Enter every field in the input table using the stated units and the exact supported selector spelling where applicable.
- Run the tool. Correct input errors before interpreting an output.
- Read the result fields below; use accompanying flags and the stated sign, boundary or model convention when interpreting a number.
Require an iceRefractiveIndex strictly between one and two. Return 2 asin(index/2), in degrees, minus 60.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| iceRefractiveIndex | Ice refractive index. | Finite number |
| Output field | Interpretation |
|---|---|
| result | Object containing the following named result fields. |
| result.minimumDeviationDegrees | Minimum deviation degrees; use the stated units and sign convention. |
{
"input": {
"iceRefractiveIndex": 1.31
},
"output": {
"result": {
"minimumDeviationDegrees": 21.839299909773032
}
}
}Limitations and assumptions
- The tool does not predict a visible sun dog, model ice-crystal orientation or solve atmospheric scattering.
- Every declared field is required and unexpected fields are rejected. Numeric inputs must be finite; input errors are distinct from a valid false result or an explicitly qualified output.
- Extremely large inputs and nonfinite or excessively large outputs are rejected. List positions reported by the tool use zero-based indices unless stated otherwise.
Alternative or Complementary methods
Check the underlying observations, units and conventions independently before using the result in a larger workflow. The tools listed below address nearby tasks; compare their inputs and scope before substituting one for this operation.
References
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