Source: https://guthlabs.ai/docs/instruments/relative-humidity-from-wet-dry-bulb/implementation/

instrument implementation / implementation-contract

# Relative Humidity from Wet/Dry Bulb implementation

A source-bound implementation contract for Relative Humidity from Wet/Dry Bulb; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-036

**Effect**: Computation or source lookup only

## Input and validation requirements

The Sprung calculation accepts physically impossible wet/dry readings that produce negative vapor pressure and a negative logarithm argument; dew point is undefined and the instrument should reject the input. The phase-table boundary and sign/unit conventions also materially affect results.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "dry_bulb_C": 20,
    "wet_bulb_C": 20,
    "station_pressure_kPa": 101.325
  },
  "expected_outputs": {
    "relative_humidity_percent": 100,
    "dew_point_C": 20,
    "vapor_pressure_hPa": 23.38
  },
  "reference_data": {
    "saturation_vapor_pressure_hPa": {
      "20_C": 23.38
    },
    "source_convention": "Widely tabulated standard meteorological value; WMO/standard water-surface saturation table",
    "pressure_conversion": {
      "101.325_kPa": 1013.25,
      "source_convention": "SI exact unit conversion"
    }
  },
  "working": "Convert pressure: p = 101.325 kPa x 10 = 1013.25 hPa. Temperature depression: Td - Tw = 20 - 20 = 0 C. A = 0.00066(1 + 0.00115 x 20) = 0.00067518. e = 23.38 - 0.00067518 x 1013.25 x 0 = 23.38 hPa. RH = 100 x e/e_s(20) = 100 x 23.38/23.38 = 100.00%. Since e equals e_s(20), dew point = 20.00 C."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/relative-humidity-from-wet-dry-bulb/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/relative-humidity-from-wet-dry-bulb/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/relative-humidity-from-wet-dry-bulb/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`