Source: https://guthlabs.ai/docs/instruments/beaufort-wind-scale-lookup/mechanism/

instrument mechanism / verified-clean

# Beaufort Wind Scale Lookup mechanism

The inspectable method record for Beaufort Wind Scale Lookup, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The specification is close to a valid WMO lookup instrument, but it needs an explicit unit contract, measurement convention, boundary policy, and clarification that the WMO table—not the approximate power-law relation—controls the Beaufort number. The honest label should state: 'Beaufort force from sustained wind speed; speed unit and averaging/reference-height convention required.'

- The relation v = 0.836·B^1.5 is only an approximate Beaufort relation when v is in m/s and B is dimensionless; it is not, by itself, the standard classification algorithm. The WMO table boundaries must define the returned category.

- The input claim 'wind speed (any unit)' is incomplete: the implementation must require a unit, convert it to the table unit, and reject or explicitly handle unknown units.

- The Beaufort scale convention requires a sustained wind-speed averaging period and reference height; standard WMO tabulations use approximately 10-minute mean wind at 10 m above open ground or sea. Gust speed, instantaneous speed, and unqualified sensor height can produce different categories.

## Units and conventions

- Lookup-table speeds are treated as 10-minute mean wind speeds at 10 m, expressed in m/s after conversion.

- For the knot test vector, 1 international knot = 0.514444 m/s.

- The approximate relation v = 0.836·B^1.5 assumes v in m/s and B as a numerical Beaufort force.

- Descriptions are the standard WMO-style land and sea descriptions; the instrument should specify which description context is displayed.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "wind_speed": 0,
    "unit": "m/s",
    "measurement": "10-minute mean at 10 m"
  },
  "expected_outputs": {
    "beaufort_number": 0,
    "land_description": "Calm; smoke rises vertically.",
    "sea_description": "Sea like a mirror."
  },
  "reference_data": {
    "beaufort_rows": [
      {
        "force": 0,
        "wind_speed_m_s": "0.0-0.2",
        "land_description": "Calm; smoke rises vertically.",
        "sea_description": "Sea like a mirror."
      }
    ],
    "source_convention": "WMO Beaufort scale, widely tabulated standard value"
  },
  "working": "Input is already in m/s: 0 m/s. The value is in the force-0 row, 0.0-0.2 m/s. Therefore Beaufort force = 0. The relation also gives v = 0.836·0^1.5 = 0 m/s, but the table determines the category."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification says wind speed may use any unit but does not define mandatory unit metadata, parsing, or behavior for extreme out-of-range values. A bare value of 10 can therefore yield B5 when read as m/s or B3 when read as mph, and an extreme finite input can overflow during conversion unless saturation or rejection is implemented.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/beaufort-wind-scale-lookup/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/beaufort-wind-scale-lookup/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/beaufort-wind-scale-lookup/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche7/tranche7-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`