Daylight Duration Latitude Calculator
Geometriccenter-of-Sunzeroaltitudedaylengthfromactualindependentdeclination,polarflagsretained,no refraction/ephemeris/cloudsunshine. Actual independent units,calibration,measurement definitions/coverage and model applicability;not a climate forecast,causal determination,geodesy operation or safe travel/design approval.
Description
Geometric daylight uses the solar center crossing an ideal zero-altitude horizon.
Geometric daylight uses the solar center crossing an ideal zero-altitude horizon.1
This tool combines latitude with an independently supplied solar declination, without calculating a calendar ephemeris, terrain horizon or atmospheric sunrise correction.
When to use Daylight Duration Latitude Calculator
Use this tool to apply the stated daylight duration latitude calculator operation with an explicit input and unit basis.
How to use Daylight Duration Latitude Calculator and how it works
- Establish the measurement basis and units described above.
- Enter actualLatitudeDegrees, callerIndependentSolarDeclinationDegrees and run the tool.
- Read result.geometricDaylightHours, result.condition using the output meanings below.
- If input is rejected, correct the stated type, range, ordering or alignment issue and rerun; review successful results under the declared convention.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualLatitudeDegrees | Latitude Degrees. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; further conditions in the algorithm |
| callerIndependentSolarDeclinationDegrees | Solar Declination Degrees. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; further conditions in the algorithm |
Require latitude and declination strictly between −90 and 90 degrees. Compute x=−tan(latitude)tan(declination); x>1 gives zero hours and never-reaches-altitude, x<−1 gives 24 hours and always-above-altitude, otherwise hours=2acos(x)/15 in degrees with condition crossing. Tangency is classified as crossing.
daylightHours = 2H/15; H = acos(−tan(latitude)tan(declination)) in degrees on the crossing branch Apply the declared units, ordering and branch conditions.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the declared output fields. | object |
| result.geometricDaylightHours | Geometric daylight duration from 0 to 24 hours. | number |
| result.condition | Branch label describing geometric crossing or noncrossing, as explained in the algorithm. | string |
{
"input": {
"actualLatitudeDegrees": 0,
"callerIndependentSolarDeclinationDegrees": 0
},
"output": {
"result": {
"geometricDaylightHours": 12,
"condition": "crossing"
}
}
}Limitations and assumptions
The output applies the declared operation to the values you supply. Establish the measurement basis, units, coefficients and any caller-selected rules before interpreting it. The tool does not independently collect or verify observations or decide whether a model or reference applies.
Supply explicit required fields with the documented types and dense aligned arrays. Unknown fields, wrong types and nonfinite numbers are rejected. Branch-specific constraints are explained above. A returned boolean, signed difference or tied result follows the stated convention; an input error instead means the required input contract was not satisfied. Very large inputs or outputs may be rejected by shared resource limits.
Alternative or Complementary methods
For a related operation, use Civil Twilight End Hour Angle. Civil twilight conventionally uses the solar center six degrees below a geometric horizon.
For a related operation, use Rise/Set Hour Angle Formula. Rise and set geometry can be formulated as crossings of a caller-selected altitude.
References
-
Daylight Duration Latitude Calculator — tool.io
Similar or alternative tools
- Civil Twilight End Hour Angle
Civil twilight conventionally uses the solar center six degrees below a geometric horizon.
- Rise/Set Hour Angle Formula
Rise and set geometry can be formulated as crossings of a caller-selected altitude.