Description
Return the north-cap whole-sphere area fraction (1-sin latitude)/2 and its south-cap complement.
Spherical geography models Earth with one radius and angular coordinates. Surface arcs, polar heights, circle radii, and area fractions are different derived quantities; an ideal spherical result does not include ellipsoid or terrain effects.
Return the north-cap whole-sphere area fraction (1-sin latitude)/2 and its south-cap complement.
When to use this tool
Use Spherical Cap Latitude Area Fraction when you need a stated spherical geographic term or angular conversion.
How to use the tool and how it works
- Enter latitudeRadians, northCap. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read fraction. Use the output convention below.
Require latitudeRadians within ±π/2. Return the north-cap whole-sphere area fraction (1-sin latitude)/2 and its south-cap complement.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| latitudeRadians | Latitude Radians | Required. Finite number. |
| northCap | North Cap | Required. Boolean. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| fraction | Dimensionless fraction, not percent: 0.1 represents 10%. | Required. Finite number. |
{
"input": {
"latitudeRadians": 0,
"northCap": true
},
"output": {
"fraction": 0.5
}
}Limitations and assumptions
- Fractions use total sphere area as denominator, not hemisphere area. The model is spherical and does not use an ellipsoid or terrain.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use ellipsoidal geodesy or a suitable terrain model when spherical assumptions are inadequate. Keep angular units, physical length units, latitude definition, and reference radius explicit.
References
Similar or alternative tools
- Geography: Spherical Cap Latitude Height
Return radius times one minus signed sine latitude for cap height inside result.
- Spherical Latitude Band Area Latitude Sensitivity
Return 2π times radius squared times cosine latitude, with positive sign for an upper boundary and negative sign for a lower boundary.