Source: https://guthlabs.ai/docs/instruments/lifting-condensation-level-lcl-height/mechanism/

instrument mechanism / verified-clean

# Lifting Condensation Level (LCL) Height mechanism

The inspectable method record for Lifting Condensation Level (LCL) Height, kept separate from implementation and qualification.

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

## Model scope

The honest-label wording correctly identifies this as a rule-of-thumb approximation. Release requires explicit temperature units, an explicit output unit or both-unit behavior, and validation that dew point is less than or equal to temperature.

- Espy's rule, LCL(m) ≈ 125·(T−Td), is a standard rule-of-thumb when T and Td are in °C (or temperature differences expressed in K) and the result is in meters.

- The specification does not define the required input temperature units or whether the output is meters, feet, or both.

- The specification does not state the domain constraint Td ≤ T; allowing Td > T produces a physically invalid negative cloud-base height.

## Units and conventions

- The coefficient 125 applies to a temperature difference in °C; a difference in kelvins has the same numerical value.

- The primary result is assumed to be in meters.

- Feet are obtained with 1 m = 3.28084 ft.

- Fahrenheit inputs must be converted to °C before applying the formula; applying 125 directly to a Fahrenheit difference is invalid.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "temperature": 25,
    "dew_point": 17,
    "temperature_unit": "°C",
    "output_unit": "m_and_ft"
  },
  "expected_outputs": {
    "lcl_height_m": 1000,
    "lcl_height_ft": 3280.84
  },
  "working": "T − Td = 25 − 17 = 8 °C. LCL = 125 × 8 = 1000 m. Feet = 1000 × 3.28084 = 3280.84 ft."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification does not define temperature units or validation behavior for Td greater than T, and an extreme but finite JavaScript input overflows to Infinity. A robust implementation should require compatible temperature units, flag negative LCL results, and handle numeric overflow explicitly.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/lifting-condensation-level-lcl-height/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/lifting-condensation-level-lcl-height/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/lifting-condensation-level-lcl-height/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-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`