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The reference · physics

The physics, coefficient by coefficient

Goable does not invent new physics, it synthesises peer-reviewed work into a single verdict. This is the index: every coefficient, what it does, where it comes from, and which register it belongs to.

01
reading the register

Read it by register, not by row

Every card looks the same until you know its register. A deterministic physics formula, a live data feed, an observation that only annotates, and a hard safety gate carry very different weight. The badge on each card tells you which one you are reading. Open a card for the structured detail: inputs and units, output, the activities that use it, its role in the verdict, the sources behind it, its limits, and the reference.

Production physics
A deterministic, peer-reviewed formula the engine evaluates directly, and whose output weighs on the 0 to 100 score.
Advisory annotation
A peer-reviewed module the pipeline evaluates live and returns in the response as an advisory or annotation, not as a weight in the 0 to 100 score.
Live data input
A measured or modelled feed blended into the state the physics reads.
Observation validation
An independent observation that checks a forecast and annotates it, never silently overrides it.
Hard safety gate
A policy check that can force an unsafe verdict independent of the rest of the score.
Calibration layer
Refits curves and confidence against accrued real outcomes.
Ensemble
Turns forecast spread into score uncertainty where ensemble coverage exists.
Research
An exploratory track, not a production input. Clearly labelled as such.
Illustrative example
One activity, read as signals. Derived from the kitesurfing entry in the activity catalog (wind, wave, tide). Other activities weight these registers differently.
SignalRoleRegister
WindPrimary suitabilityProduction physics
Gust factorConfidenceProduction physics
WavesSuitabilityProduction physics
TideTiming windowProduction physics
LightningHard safety gateHard safety gate
METAR / buoyValidationObservation validation
02
the coefficients

Every coefficient, by register

01Foundational

02Marine

03Atmospheric

04Comfort

05Hydrology

06Cryosphere

07Cross-domain

08Hazards

09Health

10Engine

03
data & observations

Four ways a number can be true

Data and validation cards carry an honest provenance label. A measured sensor reading, a satellite retrieval, a model forecast and a historical archive are not the same kind of truth, so we never present them as one. Where a representative and fresh observation exists near a spot, it corrects or annotates the forecast. Where it does not, the forecast stands on its own and confidence reflects that.

in_situ_observation
A physical sensor at or near the spot: buoy, tide gauge, airport station, strike detector.
satellite_observation
A remotely sensed measurement: sea-surface temperature, snow cover, ocean-colour water clarity.
forecast_model
A numerical model prediction: NWP fields, hydrological discharge.
reanalysis
A historical model-plus-observation archive, used as a bias baseline, not as live truth.

Confidence on a score reflects upstream forecast skill, agreement between providers and the maturity of the activity profile. A validation card never silently overrides a forecast; it annotates it with an observed value and its provenance.

04
validation & drift

How we check ourselves

05
research track

A research track, clearly labelled

Inverse Suitability (IRT)

Research

A research track exploring how continuous physical conditions and reported outcomes can separate condition difficulty from user skill.

Input
continuous physical conditions, reported outcomes
Output
estimated condition difficulty and rider skill (exploratory)
Role
Research track. Not a production input.
Limits
Exploratory. Aims to separate intrinsic condition difficulty from rider skill; results are not wired into production verdicts.
Reference
Continuous-item IRT · Marginal Maximum Likelihood · Gauss-Hermite quadrature
Read the research note
06
limitations & safety

What this is not

Goable is decision support. It does not replace local safety procedures, official warnings, instructor judgment or activity-specific regulatory requirements.

Forecasts carry uncertainty. A confident verdict is a probability, not a guarantee.

Observation validation only applies where a representative and fresh source is near the spot. Elsewhere the forecast stands alone.

Safety gates are conservative. When a safety feed is missing, the engine flags the gate as unevaluated rather than passing it silently.

The page covers activities with real hazard, including lightning, rip currents, rockfall, avalanche terrain and aviation-adjacent conditions. Treat the verdict as one input among your own checks.

07
references

The full reference list

Wind classificationBeaufort 1805 · WMO 1923
Solar position ±0.5°Meeus · Spencer 1971 · Iqbal 1983
Tide harmonicsNOAA harmonic constants
Wave energy fluxECMWF · P = ρg²H²T / 64π
Sea breeze modelMiller et al. 2003
Atmospheric stabilityPasquill–Gifford + TKE gust factor
Thermal comfortApparent temperature (Steadman 1994) · Open-Meteo feels-like
Satellite SST fusionCMEMS
Water clarity (ocean colour)Copernicus Marine Service (CMEMS) Kd490 diffuse attenuation
Surface / tidal currentCopernicus Marine Service (CMEMS) daily-mean surface current (uo/vo)
Wave height validationCopernicus Marine Service (CMEMS) wave product
Tide-gauge observationIOC Sea Level Monitoring · EMODnet
Buoy observations (wave/SST/wind)CMEMS in-situ moored buoys
River discharge validationGloFAS / Copernicus EMS river discharge
Snow-cover validationCopernicus HR-S&I satellite snow
Swell ancestryGroup-velocity back-propagation
Bathymetry contextGEBCO + spot lookup
Surface wind + visibility validationWMO FM 15-XV METAR/SPECI code · NOAA Aviation Weather Center
Convective cloud baseBolton 1980 LCL
Cross-country flight potentialComposite of convective depth, thermal strength and vertical wind shear
Fresh-snow densityHedstrom & Pomeroy 1998 · Anderson
Blowing-snow visibilitySnowfall-rate, wind and light heuristic · AMS Glossary whiteout
Lightning proximityBrooks et al. 2003 CAPE + LI
Lightning strike validationNWS Lightning Safety — the 30-30 rule
Precipitation formBourgouin 2000
Wet-bulb / WBGTStull 2011 · ISO 7243
Air-quality gateEPA AQI breakpoint tables
Rip-current modelMacMahan et al. 2006
Rockfall freeze–thawMatsuoka & Sakai 1999
Trail soil-moisture balanceFAO-56 Penman-Monteith ET₀ (Allen et al. 1998) + water balance
Marine fogKoračin et al. 2014
Density altitudeICAO Standard Atmosphere (ISO 2533)
Surf similarity / breakersBattjes 1974 · Iribarren
Breaker height shoalingMunk 1949
UV exposure doseFitzpatrick 1988 + WHO Global UV
Probabilistic ensemble30+ NWP members → distribution
ML self-calibrationIsotonic · GP · Bootstrap logistic
Inverse Suitability (IRT)Continuous-item IRT · Marginal Maximum Likelihood · Gauss-Hermite quadrature
25+ formulas · 20 physics namespaces · open catalog · CC BY 4.0