Barometric Formula (Pressure vs Altitude, general) mechanism

Model scope

NEEDS_REVIEW because the temperature, pressure, altitude, and reference-datum units are not explicitly specified. The displayed formula is standard for the isothermal ideal-gas atmosphere under the stated constant-parameter assumptions, and the honest-label warning appropriately identifies its simplification.

• The formula is correct only for an isothermal atmosphere with constant molar mass M, gravitational acceleration g, and temperature T; it is not a general barometric or ISA-layer formula.
• The specification does not state that temperature must be absolute temperature in kelvin, although using Celsius or Fahrenheit directly would make the formula invalid.
• The reference pressure P0 must be defined at the same reference datum from which altitude h is measured; calling it sea-level pressure is insufficient for locations with nonstandard reference elevations.

Units and conventions

• P0 and output P use the same pressure unit, such as pascals or kilopascals.
• Altitude h is in metres and is measured relative to the datum where P0 applies.
• Temperature T is in kelvin; Celsius must be converted with T_K = T_C + 273.15.
• M is in kg/mol, g is in m/s², and R is in J/(mol·K).
• Test calculations use M = 0.0289644 kg/mol, g = 9.80665 m/s², and R = 8.314462618 J/(mol·K).

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "P0_Pa": 101325,
    "temperature_K": 288.15,
    "altitude_m": 0
  },
  "expected_outputs": {
    "P_Pa": 101325
  },
  "working": "1. Exponent = -(Mgh)/(RT) = -(0.0289644 × 9.80665 × 0)/(8.314462618 × 288.15) = 0.\n2. exp(0) = 1.\n3. P = 101325 × 1 = 101325 Pa."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A zero-temperature input produces division by zero in the exponent and must be rejected. The specification does not state an input-domain validation rule for T <= 0.

Other records

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