Source: https://guthlabs.ai/docs/instruments/relative-humidity-dew-point-converter/

instrument / verified-clean

# Relative Humidity ↔ Dew Point Converter

The current ledger marks this instrument verified clean within the source-bound verification corpus.

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

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/relative-humidity-dew-point-converter/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/relative-humidity-dew-point-converter/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/relative-humidity-dew-point-converter/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/relative-humidity-dew-point-converter/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Thermodynamics, Fluids & Aero

**Tranche**: tranche-4

**Evidence ID**: t4-048

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The forward formula is correct under the stated assumptions, but the coefficient values, inverse formula, valid input domains, and temperature-unit contract must be specified before release. Verdict is NEEDS_REVIEW because these ambiguities affect correctness and implementation.

### Formula and scope findings

- The Magnus dew-point formula is standard only after specifying the coefficient set; a and b are not given. The test vectors below assume a=17.62 and b=243.12.

- The specification claims bidirectional conversion, but it provides only the forward dew-point formula. The inverse formula for relative humidity is missing: RH=100·exp(γ−aT/(b+T)), where γ=a·Td/(b+Td).

- The claimed ±0.4°C typical accuracy is coefficient-, temperature-, and humidity-range-dependent and must not be presented as universal.

### Unit assumptions

- T, Td, and the Magnus coefficients use degrees Celsius; Fahrenheit or Kelvin inputs require explicit conversion before applying the formula.

- RH is a percentage in the range 0<RH≤100; RH=100 means saturation.

- For the vectors, a=17.62 and b=243.12°C are assumed.

- ln is the natural logarithm and exp is the natural exponential function.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The formula has an undefined RH=0 input that requires validation, and an unlabeled RH value such as 0.5 can produce either 9.25519°C or −44.60415°C depending on percent-versus-fraction convention.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "dry_bulb_temperature_C": 20,
    "relative_humidity_percent": 50
  },
  "expected_outputs": {
    "dew_point_temperature_C": 9.2552
  },
  "working": "γ=ln(50/100)+(17.62×20)/(243.12+20) = ln(0.5)+352.4/263.12 = -0.693147+1.339313 = 0.646166. Td=243.12×0.646166/(17.62-0.646166) = 157.0958/16.973834 = 9.2552°C."
}
````

## Related workflows

[Weather Stationcross-check pair](<https://guthlabs.ai/docs/instrument-workflows/weather-station/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`