FA-70931 / Weather index computation / Open access

Shade apparent temperature: wind speed units · case 01

Breezy days feel implausibly cold; a 36 km/h wind lowers the value by 25 degrees.

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

ROOT CAUSE

Wind in km/h is used where the formula expects m/s.

VERIFIED REPAIR

Convert with km/h / 3.6.

Unsuccessful approach: Dividing by 1.609344 converts to mph, still overstating the wind term.

Case contract

Input air temperature degC, RH percent, wind in km/h measured at 10 m. e = RH/100*6.105*exp(17.27*Ta/(237.7+Ta)) hPa; wind in m/s = km/h / 3.6; AT = Ta + 0.33e - 0.70ws - 4.00 rounded to 0.1.

Why this case matters

Feels-like temperature on consumer forecasts uses this non-radiative apparent temperature.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(ta, rh, wind_kmh):
    e = rh / 100.0 * 6.105 * math.exp(17.27 * ta / (237.7 + ta))
    ws = wind_kmh
    at = ta + 0.33 * e - 0.70 * ws - 4.00
    return round(at, 1)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['-5 C 10% RH wind 0 km/h', [-5, 10, 0], -8.9], ['-5 C 10% RH wind 10 km/h', [-5, 10, 10], -10.8], ['-5 C 10% RH wind 36 km/h', [-5, 10, 36], -15.9], ['-5 C 10% RH wind 72 km/h', [-5, 10, 72], -22.9], ['-5 C 50% RH wind 0 km/h', [-5, 50, 0], -8.3], ['-5 C 50% RH wind 10 km/h', [-5, 50, 10], -10.2], ['-5 C 50% RH wind 36 km/h', [-5, 50, 36], -15.3], ['-5 C 50% RH wind 72 km/h', [-5, 50, 72], -22.3]], [['-5 C 50% RH wind 10 km/h', [-5, 50, 10], -10.2], ['-5 C 50% RH wind 72 km/h', [-5, 50, 72], -22.3], ['-5 C 90% RH wind 0 km/h', [-5, 90, 0], -7.7], ['-5 C 90% RH wind 10 km/h', [-5, 90, 10], -9.7], ['-5 C 90% RH wind 36 km/h', [-5, 90, 36], -14.7], ['-5 C 90% RH wind 72 km/h', [-5, 90, 72], -21.7], ['0 C 10% RH wind 0 km/h', [0, 10, 0], -3.8], ['0 C 10% RH wind 10 km/h', [0, 10, 10], -5.7]], [['-5 C 90% RH wind 10 km/h', [-5, 90, 10], -9.7], ['0 C 10% RH wind 36 km/h', [0, 10, 36], -10.8], ['0 C 10% RH wind 72 km/h', [0, 10, 72], -17.8], ['0 C 50% RH wind 0 km/h', [0, 50, 0], -3.0], ['0 C 50% RH wind 10 km/h', [0, 50, 10], -4.9], ['0 C 50% RH wind 36 km/h', [0, 50, 36], -10.0], ['0 C 50% RH wind 72 km/h', [0, 50, 72], -17.0], ['0 C 90% RH wind 0 km/h', [0, 90, 0], -2.2]], [['0 C 10% RH wind 10 km/h', [0, 10, 10], -5.7], ['0 C 90% RH wind 10 km/h', [0, 90, 10], -4.1], ['0 C 90% RH wind 36 km/h', [0, 90, 36], -9.2], ['0 C 90% RH wind 72 km/h', [0, 90, 72], -16.2], ['12 C 10% RH wind 0 km/h', [12, 10, 0], 8.5], ['12 C 10% RH wind 10 km/h', [12, 10, 10], 6.5], ['12 C 10% RH wind 36 km/h', [12, 10, 36], 1.5], ['12 C 10% RH wind 72 km/h', [12, 10, 72], -5.5]], [['0 C 50% RH wind 10 km/h', [0, 50, 10], -4.9], ['12 C 50% RH wind 0 km/h', [12, 50, 0], 10.3], ['12 C 50% RH wind 10 km/h', [12, 50, 10], 8.4], ['12 C 50% RH wind 36 km/h', [12, 50, 36], 3.3], ['12 C 50% RH wind 72 km/h', [12, 50, 72], -3.7], ['12 C 90% RH wind 0 km/h', [12, 90, 0], 12.2], ['12 C 90% RH wind 10 km/h', [12, 90, 10], 10.2], ['12 C 90% RH wind 36 km/h', [12, 90, 36], 5.2]]]
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 fixture	Actual	Expected	Outcome
-5 C 10% RH wind 0 km/h	`-8.9`	`-8.9`	Passed
-5 C 10% RH wind 10 km/h	`-15.9`	`-10.8`	Failed
-5 C 10% RH wind 36 km/h	`-34.1`	`-15.9`	Failed
-5 C 10% RH wind 72 km/h	`-59.3`	`-22.9`	Failed
-5 C 50% RH wind 0 km/h	`-8.3`	`-8.3`	Passed
-5 C 50% RH wind 10 km/h	`-15.3`	`-10.2`	Failed
-5 C 50% RH wind 36 km/h	`-33.5`	`-15.3`	Failed
-5 C 50% RH wind 72 km/h	`-58.7`	`-22.3`	Failed

SHA-256 / 573612d68f5f87d4349f0ee8133c1e54215282dec9a6d395add045988362e816

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(ta, rh, wind_kmh):
    e = rh / 100.0 * 6.105 * math.exp(17.27 * ta / (237.7 + ta))
    ws = wind_kmh / 1.609344
    at = ta + 0.33 * e - 0.70 * ws - 4.00
    return round(at, 1)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['-5 C 10% RH wind 0 km/h', [-5, 10, 0], -8.9], ['-5 C 10% RH wind 10 km/h', [-5, 10, 10], -10.8], ['-5 C 10% RH wind 36 km/h', [-5, 10, 36], -15.9], ['-5 C 10% RH wind 72 km/h', [-5, 10, 72], -22.9], ['-5 C 50% RH wind 0 km/h', [-5, 50, 0], -8.3], ['-5 C 50% RH wind 10 km/h', [-5, 50, 10], -10.2], ['-5 C 50% RH wind 36 km/h', [-5, 50, 36], -15.3], ['-5 C 50% RH wind 72 km/h', [-5, 50, 72], -22.3]], [['-5 C 50% RH wind 10 km/h', [-5, 50, 10], -10.2], ['-5 C 50% RH wind 72 km/h', [-5, 50, 72], -22.3], ['-5 C 90% RH wind 0 km/h', [-5, 90, 0], -7.7], ['-5 C 90% RH wind 10 km/h', [-5, 90, 10], -9.7], ['-5 C 90% RH wind 36 km/h', [-5, 90, 36], -14.7], ['-5 C 90% RH wind 72 km/h', [-5, 90, 72], -21.7], ['0 C 10% RH wind 0 km/h', [0, 10, 0], -3.8], ['0 C 10% RH wind 10 km/h', [0, 10, 10], -5.7]], [['-5 C 90% RH wind 10 km/h', [-5, 90, 10], -9.7], ['0 C 10% RH wind 36 km/h', [0, 10, 36], -10.8], ['0 C 10% RH wind 72 km/h', [0, 10, 72], -17.8], ['0 C 50% RH wind 0 km/h', [0, 50, 0], -3.0], ['0 C 50% RH wind 10 km/h', [0, 50, 10], -4.9], ['0 C 50% RH wind 36 km/h', [0, 50, 36], -10.0], ['0 C 50% RH wind 72 km/h', [0, 50, 72], -17.0], ['0 C 90% RH wind 0 km/h', [0, 90, 0], -2.2]], [['0 C 10% RH wind 10 km/h', [0, 10, 10], -5.7], ['0 C 90% RH wind 10 km/h', [0, 90, 10], -4.1], ['0 C 90% RH wind 36 km/h', [0, 90, 36], -9.2], ['0 C 90% RH wind 72 km/h', [0, 90, 72], -16.2], ['12 C 10% RH wind 0 km/h', [12, 10, 0], 8.5], ['12 C 10% RH wind 10 km/h', [12, 10, 10], 6.5], ['12 C 10% RH wind 36 km/h', [12, 10, 36], 1.5], ['12 C 10% RH wind 72 km/h', [12, 10, 72], -5.5]], [['0 C 50% RH wind 10 km/h', [0, 50, 10], -4.9], ['12 C 50% RH wind 0 km/h', [12, 50, 0], 10.3], ['12 C 50% RH wind 10 km/h', [12, 50, 10], 8.4], ['12 C 50% RH wind 36 km/h', [12, 50, 36], 3.3], ['12 C 50% RH wind 72 km/h', [12, 50, 72], -3.7], ['12 C 90% RH wind 0 km/h', [12, 90, 0], 12.2], ['12 C 90% RH wind 10 km/h', [12, 90, 10], 10.2], ['12 C 90% RH wind 36 km/h', [12, 90, 36], 5.2]]]
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 fixture	Actual	Expected	Outcome
-5 C 10% RH wind 0 km/h	`-8.9`	`-8.9`	Passed
-5 C 10% RH wind 10 km/h	`-13.2`	`-10.8`	Failed
-5 C 10% RH wind 36 km/h	`-24.5`	`-15.9`	Failed
-5 C 10% RH wind 72 km/h	`-40.2`	`-22.9`	Failed
-5 C 50% RH wind 0 km/h	`-8.3`	`-8.3`	Passed
-5 C 50% RH wind 10 km/h	`-12.7`	`-10.2`	Failed
-5 C 50% RH wind 36 km/h	`-24.0`	`-15.3`	Failed
-5 C 50% RH wind 72 km/h	`-39.6`	`-22.3`	Failed

SHA-256 / 54b668bc91073803a725b3baf67fba8e81e074ec0e68a49b6bf4cfc9619d162e

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(ta, rh, wind_kmh):
    e = rh / 100.0 * 6.105 * math.exp(17.27 * ta / (237.7 + ta))
    ws = wind_kmh / 3.6
    at = ta + 0.33 * e - 0.70 * ws - 4.00
    return round(at, 1)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['-5 C 10% RH wind 0 km/h', [-5, 10, 0], -8.9], ['-5 C 10% RH wind 10 km/h', [-5, 10, 10], -10.8], ['-5 C 10% RH wind 36 km/h', [-5, 10, 36], -15.9], ['-5 C 10% RH wind 72 km/h', [-5, 10, 72], -22.9], ['-5 C 50% RH wind 0 km/h', [-5, 50, 0], -8.3], ['-5 C 50% RH wind 10 km/h', [-5, 50, 10], -10.2], ['-5 C 50% RH wind 36 km/h', [-5, 50, 36], -15.3], ['-5 C 50% RH wind 72 km/h', [-5, 50, 72], -22.3]], [['-5 C 50% RH wind 10 km/h', [-5, 50, 10], -10.2], ['-5 C 50% RH wind 72 km/h', [-5, 50, 72], -22.3], ['-5 C 90% RH wind 0 km/h', [-5, 90, 0], -7.7], ['-5 C 90% RH wind 10 km/h', [-5, 90, 10], -9.7], ['-5 C 90% RH wind 36 km/h', [-5, 90, 36], -14.7], ['-5 C 90% RH wind 72 km/h', [-5, 90, 72], -21.7], ['0 C 10% RH wind 0 km/h', [0, 10, 0], -3.8], ['0 C 10% RH wind 10 km/h', [0, 10, 10], -5.7]], [['-5 C 90% RH wind 10 km/h', [-5, 90, 10], -9.7], ['0 C 10% RH wind 36 km/h', [0, 10, 36], -10.8], ['0 C 10% RH wind 72 km/h', [0, 10, 72], -17.8], ['0 C 50% RH wind 0 km/h', [0, 50, 0], -3.0], ['0 C 50% RH wind 10 km/h', [0, 50, 10], -4.9], ['0 C 50% RH wind 36 km/h', [0, 50, 36], -10.0], ['0 C 50% RH wind 72 km/h', [0, 50, 72], -17.0], ['0 C 90% RH wind 0 km/h', [0, 90, 0], -2.2]], [['0 C 10% RH wind 10 km/h', [0, 10, 10], -5.7], ['0 C 90% RH wind 10 km/h', [0, 90, 10], -4.1], ['0 C 90% RH wind 36 km/h', [0, 90, 36], -9.2], ['0 C 90% RH wind 72 km/h', [0, 90, 72], -16.2], ['12 C 10% RH wind 0 km/h', [12, 10, 0], 8.5], ['12 C 10% RH wind 10 km/h', [12, 10, 10], 6.5], ['12 C 10% RH wind 36 km/h', [12, 10, 36], 1.5], ['12 C 10% RH wind 72 km/h', [12, 10, 72], -5.5]], [['0 C 50% RH wind 10 km/h', [0, 50, 10], -4.9], ['12 C 50% RH wind 0 km/h', [12, 50, 0], 10.3], ['12 C 50% RH wind 10 km/h', [12, 50, 10], 8.4], ['12 C 50% RH wind 36 km/h', [12, 50, 36], 3.3], ['12 C 50% RH wind 72 km/h', [12, 50, 72], -3.7], ['12 C 90% RH wind 0 km/h', [12, 90, 0], 12.2], ['12 C 90% RH wind 10 km/h', [12, 90, 10], 10.2], ['12 C 90% RH wind 36 km/h', [12, 90, 36], 5.2]]]
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 fixture	Actual	Expected	Outcome
-5 C 10% RH wind 0 km/h	`-8.9`	`-8.9`	Passed
-5 C 10% RH wind 10 km/h	`-10.8`	`-10.8`	Passed
-5 C 10% RH wind 36 km/h	`-15.9`	`-15.9`	Passed
-5 C 10% RH wind 72 km/h	`-22.9`	`-22.9`	Passed
-5 C 50% RH wind 0 km/h	`-8.3`	`-8.3`	Passed
-5 C 50% RH wind 10 km/h	`-10.2`	`-10.2`	Passed
-5 C 50% RH wind 36 km/h	`-15.3`	`-15.3`	Passed
-5 C 50% RH wind 72 km/h	`-22.3`	`-22.3`	Passed

SHA-256 / 2c5326c695f0a4664a65b5a92f56ba4ee02630b275fd0ca145c11a792a09feb5

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 2026-09-29T14:48:25.155129+00:00.

Case digest / d00baca7d12061a6eb72e28e445b4c66153875cf789f7585dbed778474760098