A glass dome split into 12 hour wedges. A rotating hour hand triggers a real weather phenomenon in each wedge, with the physics numbers live.
One lap is 6 minutes at 1x (30 s per hour). Click a wedge in the 3D view, or a button below, to trigger that hour.
Sunset and night shift the base temperature by -3 and -7 degrees C and raise humidity, which matters for fog.
High is the default on every device. Low renders at 1x pixel ratio with fewer particles and smaller shadow maps.
Each check recomputes a result with a separate numerical method (time stepping, integration, closed form) and compares it with the formula the simulation uses.
Scale: one scene unit is 250 m, so the island is about 5 km across and the observer (a weather station) stands at the hub of the clock. All twelve wedges are teaching models with one governing idea each; they run in compressed time and are drawn with exaggerated heights.
Ice and graupel collisions separate charge until the field in the cloud reaches the initiation value (about 300 kV/m here, far below the 3 MV/m of dry air in a lab because of precipitation particles). A strike then relaxes the field. Light arrives at once; sound travels at c = 331.3 sqrt(1 + T/273.15) m/s.
Dew point from the Magnus formula. When the air cools below it, the excess vapour condenses: LWC = rho_sat(Td) - rho_sat(T). Kunkel's fit gives the extinction, and Koschmieder's law the visual range.
Marshall-Palmer drop sizes (median diameter D0 = 0.9 R^0.21 mm) and a Gunn-Kinzer style fall speed v = 9.65 - 10.3 exp(-0.6 D). When the rain rate exceeds the drainage capacity (20 mm/h here) the excess accumulates as a puddle.
A 2.5 cm stone falls near 20 m/s and carries about 1.5 J. Real stones are not smooth spheres, so Cd varies from 0.5 to 1.0.
With the dew point fixed, heating lowers relative humidity. The NWS Rothfusz regression turns temperature and humidity into an apparent temperature (valid roughly above 27 C).
PM2.5 bands follow the US EPA 2024 index breakpoints. The spread law and emission factor (12 g/kg) are simplified.
Depth is solved from Q by bisection. The bridge deck is overtopped above 1.5 m. Real catchments add routing delay and infiltration.
EF ratings use 3-second gust speeds in miles per hour. The funnel is drawn about twice as wide as its scale for visibility. Debris orbits with the true angular speed v(r)/r.
Snowfall rate S (liquid equivalent) fixes the flake count N = S / (volume x density ratio x fall speed) for 3 mm flakes of density 100 kg/m3. Then beta = N x 2 x (pi D^2 / 4) and V = 3.912 / beta, giving a few hundred metres at 5 mm/h. Wind chill is the Canadian/US formula.
Hargreaves evapotranspiration ET0 = 0.0023 Ra (T + 17.8) sqrt(dT) with Ra = 16 mm/day equivalent and dT = 12 C drains a 150 mm soil store; evaporation slows once the store falls below half. Six model days pass per second.
The dense cold air wedges under warm air on a slope of order 1:100 to 1:200. Pressure rises and the wind veers as the front passes.
Heights, sizes and time are compressed; the dome is one island, so winds and clouds are confined to wedges. The numbers are textbook models for teaching, not a forecast. Independent educational model; no characters, no trade dress, no affiliation with any film, game or organisation.