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FA-70956 / Weather index computation / Open access

Livestock temperature-humidity index: Fahrenheit depression term · case 01

THI drifts upward and moderate stress is reported too early.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The humidity depression term uses Celsius temperature where the formula works in Fahrenheit.

VERIFIED REPAIR

Use (1.8T - 26).

Unsuccessful approach: Parenthesising as 1.8*(T - 26) subtracts 46.8 instead of 26.

Case contract

Input barn temperature degC and RH percent. THI = (1.8T+32) - (0.55 - 0.0055RH)(1.8T - 26); THI is rounded to 0.1 first and the stress level is taken from the rounded value: <72 none, <79 mild, <89 moderate, <99 severe, else emergency.

Why this case matters

Dairy heat-stress alerts and cooling automation key off THI bands.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(t_c, rh):
    thi = (1.8 * t_c + 32) - (0.55 - 0.0055 * rh) * (t_c - 26)
    thi = round(thi, 1)
    if thi < 72:
        level = "none"
    elif thi < 79:
        level = "mild"
    elif thi < 89:
        level = "moderate"
    elif thi < 99:
        level = "severe"
    else:
        level = "emergency"
    return [thi, level]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['15 C barn at 20% RH', [15, 20], [58.6, 'none']], ['15 C barn at 40% RH', [15, 40], [58.7, 'none']], ['15 C barn at 55% RH', [15, 55], [58.8, 'none']], ['15 C barn at 70% RH', [15, 70], [58.8, 'none']], ['15 C barn at 85% RH', [15, 85], [58.9, 'none']], ['15 C barn at 100% RH', [15, 100], [59.0, 'none']], ['21 C barn at 20% RH', [21, 20], [64.6, 'none']], ['21 C barn at 40% RH', [21, 40], [65.9, 'none']]], [['15 C barn at 70% RH', [15, 70], [58.8, 'none']], ['21 C barn at 40% RH', [21, 40], [65.9, 'none']], ['21 C barn at 55% RH', [21, 55], [66.9, 'none']], ['21 C barn at 70% RH', [21, 70], [67.9, 'none']], ['21 C barn at 85% RH', [21, 85], [68.8, 'none']], ['21 C barn at 100% RH', [21, 100], [69.8, 'none']], ['22 C barn at 20% RH', [22, 20], [65.6, 'none']], ['22 C barn at 40% RH', [22, 40], [67.1, 'none']]], [['21 C barn at 40% RH', [21, 40], [65.9, 'none']], ['22 C barn at 40% RH', [22, 40], [67.1, 'none']], ['22 C barn at 55% RH', [22, 55], [68.2, 'none']], ['22 C barn at 70% RH', [22, 70], [69.4, 'none']], ['22 C barn at 85% RH', [22, 85], [70.5, 'none']], ['22 C barn at 100% RH', [22, 100], [71.6, 'none']], ['24 C barn at 20% RH', [24, 20], [67.6, 'none']], ['24 C barn at 40% RH', [24, 40], [69.5, 'none']]], [['21 C barn at 85% RH', [21, 85], [68.8, 'none']], ['24 C barn at 40% RH', [24, 40], [69.5, 'none']], ['24 C barn at 70% RH', [24, 70], [72.4, 'mild']], ['24 C barn at 85% RH', [24, 85], [73.8, 'mild']], ['24 C barn at 100% RH', [24, 100], [75.2, 'mild']], ['25 C barn at 20% RH', [25, 20], [68.6, 'none']], ['25 C barn at 40% RH', [25, 40], [70.7, 'none']], ['25 C barn at 55% RH', [25, 55], [72.3, 'mild']]], [['22 C barn at 55% RH', [22, 55], [68.2, 'none']], ['25 C barn at 40% RH', [25, 40], [70.7, 'none']], ['25 C barn at 85% RH', [25, 85], [75.4, 'mild']], ['25 C barn at 100% RH', [25, 100], [77.0, 'mild']], ['26 C barn at 20% RH', [26, 20], [69.6, 'none']], ['26 C barn at 40% RH', [26, 40], [71.9, 'none']], ['26 C barn at 55% RH', [26, 55], [73.7, 'mild']], ['26 C barn at 70% RH', [26, 70], [75.4, 'mild']]]]
for label, args, expected in fixtures[N - 1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
15 C barn at 20% RH[63.8, 'none'][58.6, 'none']Failed
15 C barn at 40% RH[62.6, 'none'][58.7, 'none']Failed
15 C barn at 55% RH[61.7, 'none'][58.8, 'none']Failed
15 C barn at 70% RH[60.8, 'none'][58.8, 'none']Failed
15 C barn at 85% RH[59.9, 'none'][58.9, 'none']Failed
15 C barn at 100% RH[59.0, 'none'][59.0, 'none']Passed
21 C barn at 20% RH[72.0, 'mild'][64.6, 'none']Failed
21 C barn at 40% RH[71.5, 'none'][65.9, 'none']Failed

SHA-256 / 081143f9d852bd71db0ea5cb489285dc00d4a752c89b1d117d64b29e6f171fa1

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(t_c, rh):
    thi = (1.8 * t_c + 32) - (0.55 - 0.0055 * rh) * (1.8 * (t_c - 26))
    thi = round(thi, 1)
    if thi < 72:
        level = "none"
    elif thi < 79:
        level = "mild"
    elif thi < 89:
        level = "moderate"
    elif thi < 99:
        level = "severe"
    else:
        level = "emergency"
    return [thi, level]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['15 C barn at 20% RH', [15, 20], [58.6, 'none']], ['15 C barn at 40% RH', [15, 40], [58.7, 'none']], ['15 C barn at 55% RH', [15, 55], [58.8, 'none']], ['15 C barn at 70% RH', [15, 70], [58.8, 'none']], ['15 C barn at 85% RH', [15, 85], [58.9, 'none']], ['15 C barn at 100% RH', [15, 100], [59.0, 'none']], ['21 C barn at 20% RH', [21, 20], [64.6, 'none']], ['21 C barn at 40% RH', [21, 40], [65.9, 'none']]], [['15 C barn at 70% RH', [15, 70], [58.8, 'none']], ['21 C barn at 40% RH', [21, 40], [65.9, 'none']], ['21 C barn at 55% RH', [21, 55], [66.9, 'none']], ['21 C barn at 70% RH', [21, 70], [67.9, 'none']], ['21 C barn at 85% RH', [21, 85], [68.8, 'none']], ['21 C barn at 100% RH', [21, 100], [69.8, 'none']], ['22 C barn at 20% RH', [22, 20], [65.6, 'none']], ['22 C barn at 40% RH', [22, 40], [67.1, 'none']]], [['21 C barn at 40% RH', [21, 40], [65.9, 'none']], ['22 C barn at 40% RH', [22, 40], [67.1, 'none']], ['22 C barn at 55% RH', [22, 55], [68.2, 'none']], ['22 C barn at 70% RH', [22, 70], [69.4, 'none']], ['22 C barn at 85% RH', [22, 85], [70.5, 'none']], ['22 C barn at 100% RH', [22, 100], [71.6, 'none']], ['24 C barn at 20% RH', [24, 20], [67.6, 'none']], ['24 C barn at 40% RH', [24, 40], [69.5, 'none']]], [['21 C barn at 85% RH', [21, 85], [68.8, 'none']], ['24 C barn at 40% RH', [24, 40], [69.5, 'none']], ['24 C barn at 70% RH', [24, 70], [72.4, 'mild']], ['24 C barn at 85% RH', [24, 85], [73.8, 'mild']], ['24 C barn at 100% RH', [24, 100], [75.2, 'mild']], ['25 C barn at 20% RH', [25, 20], [68.6, 'none']], ['25 C barn at 40% RH', [25, 40], [70.7, 'none']], ['25 C barn at 55% RH', [25, 55], [72.3, 'mild']]], [['22 C barn at 55% RH', [22, 55], [68.2, 'none']], ['25 C barn at 40% RH', [25, 40], [70.7, 'none']], ['25 C barn at 85% RH', [25, 85], [75.4, 'mild']], ['25 C barn at 100% RH', [25, 100], [77.0, 'mild']], ['26 C barn at 20% RH', [26, 20], [69.6, 'none']], ['26 C barn at 40% RH', [26, 40], [71.9, 'none']], ['26 C barn at 55% RH', [26, 55], [73.7, 'mild']], ['26 C barn at 70% RH', [26, 70], [75.4, 'mild']]]]
for label, args, expected in fixtures[N - 1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
15 C barn at 20% RH[67.7, 'none'][58.6, 'none']Failed
15 C barn at 40% RH[65.5, 'none'][58.7, 'none']Failed
15 C barn at 55% RH[63.9, 'none'][58.8, 'none']Failed
15 C barn at 70% RH[62.3, 'none'][58.8, 'none']Failed
15 C barn at 85% RH[60.6, 'none'][58.9, 'none']Failed
15 C barn at 100% RH[59.0, 'none'][59.0, 'none']Passed
21 C barn at 20% RH[73.8, 'mild'][64.6, 'none']Failed
21 C barn at 40% RH[72.8, 'mild'][65.9, 'none']Failed

SHA-256 / e4ce7d450097ed6c4d413b0b0de1fd037b99f1cb835b8d110f9de8234073b787

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(t_c, rh):
    thi = (1.8 * t_c + 32) - (0.55 - 0.0055 * rh) * (1.8 * t_c - 26)
    thi = round(thi, 1)
    if thi < 72:
        level = "none"
    elif thi < 79:
        level = "mild"
    elif thi < 89:
        level = "moderate"
    elif thi < 99:
        level = "severe"
    else:
        level = "emergency"
    return [thi, level]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['15 C barn at 20% RH', [15, 20], [58.6, 'none']], ['15 C barn at 40% RH', [15, 40], [58.7, 'none']], ['15 C barn at 55% RH', [15, 55], [58.8, 'none']], ['15 C barn at 70% RH', [15, 70], [58.8, 'none']], ['15 C barn at 85% RH', [15, 85], [58.9, 'none']], ['15 C barn at 100% RH', [15, 100], [59.0, 'none']], ['21 C barn at 20% RH', [21, 20], [64.6, 'none']], ['21 C barn at 40% RH', [21, 40], [65.9, 'none']]], [['15 C barn at 70% RH', [15, 70], [58.8, 'none']], ['21 C barn at 40% RH', [21, 40], [65.9, 'none']], ['21 C barn at 55% RH', [21, 55], [66.9, 'none']], ['21 C barn at 70% RH', [21, 70], [67.9, 'none']], ['21 C barn at 85% RH', [21, 85], [68.8, 'none']], ['21 C barn at 100% RH', [21, 100], [69.8, 'none']], ['22 C barn at 20% RH', [22, 20], [65.6, 'none']], ['22 C barn at 40% RH', [22, 40], [67.1, 'none']]], [['21 C barn at 40% RH', [21, 40], [65.9, 'none']], ['22 C barn at 40% RH', [22, 40], [67.1, 'none']], ['22 C barn at 55% RH', [22, 55], [68.2, 'none']], ['22 C barn at 70% RH', [22, 70], [69.4, 'none']], ['22 C barn at 85% RH', [22, 85], [70.5, 'none']], ['22 C barn at 100% RH', [22, 100], [71.6, 'none']], ['24 C barn at 20% RH', [24, 20], [67.6, 'none']], ['24 C barn at 40% RH', [24, 40], [69.5, 'none']]], [['21 C barn at 85% RH', [21, 85], [68.8, 'none']], ['24 C barn at 40% RH', [24, 40], [69.5, 'none']], ['24 C barn at 70% RH', [24, 70], [72.4, 'mild']], ['24 C barn at 85% RH', [24, 85], [73.8, 'mild']], ['24 C barn at 100% RH', [24, 100], [75.2, 'mild']], ['25 C barn at 20% RH', [25, 20], [68.6, 'none']], ['25 C barn at 40% RH', [25, 40], [70.7, 'none']], ['25 C barn at 55% RH', [25, 55], [72.3, 'mild']]], [['22 C barn at 55% RH', [22, 55], [68.2, 'none']], ['25 C barn at 40% RH', [25, 40], [70.7, 'none']], ['25 C barn at 85% RH', [25, 85], [75.4, 'mild']], ['25 C barn at 100% RH', [25, 100], [77.0, 'mild']], ['26 C barn at 20% RH', [26, 20], [69.6, 'none']], ['26 C barn at 40% RH', [26, 40], [71.9, 'none']], ['26 C barn at 55% RH', [26, 55], [73.7, 'mild']], ['26 C barn at 70% RH', [26, 70], [75.4, 'mild']]]]
for label, args, expected in fixtures[N - 1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
15 C barn at 20% RH[58.6, 'none'][58.6, 'none']Passed
15 C barn at 40% RH[58.7, 'none'][58.7, 'none']Passed
15 C barn at 55% RH[58.8, 'none'][58.8, 'none']Passed
15 C barn at 70% RH[58.8, 'none'][58.8, 'none']Passed
15 C barn at 85% RH[58.9, 'none'][58.9, 'none']Passed
15 C barn at 100% RH[59.0, 'none'][59.0, 'none']Passed
21 C barn at 20% RH[64.6, 'none'][64.6, 'none']Passed
21 C barn at 40% RH[65.9, 'none'][65.9, 'none']Passed

SHA-256 / 642a124f4a5b6f359d8950426e7d5df6e9c1fbc77d4581af7aa6b0af0fe77fa2

Verification & scope

Stipulated deterministic teaching model of an operational weather index; coefficients and thresholds are fixed by the contract and no claim of standards conformance is made. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:48:25.437099+00:00.

Case digest / 139433aba67865f68894ab8cdc8aa6f784d5820c8eb7257379adcc6172a98b62