Source: https://guthlabs.ai/docs/instruments/wet-bulb-temperature-estimator/

instrument / verified-clean

# Wet-Bulb Temperature Estimator

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/wet-bulb-temperature-estimator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/wet-bulb-temperature-estimator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/wet-bulb-temperature-estimator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/wet-bulb-temperature-estimator/qualification/>)

## Ledger state

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

**Area**: Thermodynamics, Fluids & Aero

**Tranche**: tranche-6

**Evidence ID**: t6-015

**Ledger rows**: 1

No ledger note is attached.

## Review findings

NEEDS_REVIEW because the instrument does not define which of the two claimed algorithms is authoritative. For a deterministic plain-arithmetic implementation, explicitly select Stull (2011), document that pressure is ignored, validate T and RH, and label the output as an empirical approximation. Alternatively, specify the complete pressure-dependent iterative psychrometric model and convergence tolerance.

### Formula and scope findings

- The specification names two materially different algorithms—Stull (2011) and an iterative psychrometric energy balance—but does not select one or define the iterative equations, psychrometric constants, saturation-vapor-pressure correlation, or convergence criterion.

- The Stull formula does not use barometric pressure, so the declared P input is ignored when that method is selected. Pressure is required for a pressure-aware psychrometric calculation.

- The Stull correlation is an empirical approximation, not a general psychrometric energy-balance solution; its stated approximate validity range and error should be displayed honestly.

### Unit assumptions

- Stull inputs are dry-bulb temperature T in degrees Celsius and relative humidity RH in percent from 0 to 100, not a fraction from 0 to 1.

- The Stull formula uses inverse trigonometric functions in radians.

- Barometric pressure P is not used by the Stull formula. If P is intended to affect the result, its units and the complete pressure-corrected algorithm must be specified.

- Outputs are degrees Celsius when T is supplied in degrees Celsius.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

A negative-RH input drives the RH^(3/2) term outside the real-number domain and can yield NaN unless rejected. The specification also leaves the Stull-versus-iterative method and the validity-limit branch unspecified, while RH unit convention can be interpreted as either percent or fraction.

## 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": {
    "method": "Stull 2011",
    "dry_bulb_C": 20,
    "RH_percent": 50,
    "pressure_kPa": 101.325
  },
  "expected_outputs": {
    "wet_bulb_C": 13.699
  },
  "working": "Use Tw = T*atan(0.151977*sqrt(RH+8.313659)) + atan(T+RH) - atan(RH-1.676331) + 0.00391838*RH^(3/2)*atan(0.023101*RH) - 4.686035. sqrt(50+8.313659)=sqrt(58.313659)=7.63634. First angle: atan(0.151977*7.63634)=atan(1.16055)=0.859571, so T term=20*0.859571=17.1914. atan(20+50)=atan(70)=1.556512. atan(50-1.676331)=atan(48.323669)=1.550105. RH term: 50^(3/2)=353.553; 0.00391838*353.553=1.38536; atan(0.023101*50)=atan(1.15505)=0.857222; product=1.18756. Therefore Tw=17.1914+1.556512-1.550105+1.18756-4.686035=13.6993 C, or 13.699 C. P is unused."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## 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-tranche6/tranche6-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`