Weather

Weather System Overview

The weather simulation in Rise: The Vieneo Province has evolved into a sophisticated planetary model with dynamic interactions between temperature, humidity, convection, terrain, wind, and time of day. The system calculates per-location weather conditions using multiple global maps and simulated environmental physics.

Core Maps Used

Vapor Map: Used for relative humidity and dew point derivation.

Temperature Deviation Map: Provides baseline surface temperature adjusted seasonally and diurnally.

Convection Map: Used to estimate atmospheric turbulence and storm potential.

Wind Speed Map: Determines baseline wind speeds.

Wind Direction Map: Directional input used for orographic lifting and directional wind effects.

Elevation Map: Determines local and upwind terrain for visibility and ceiling calculations.

Diurnal and Seasonal Effects

Local temperature is modulated by time of day and seasonal solar latitude offset.

Peak surface temperature occurs 4 hours after solar noon.

Seasonal temperature swing ranges from +12.15°C to -10.64°C based on distance from solar sublatitude.

Temperature and Dew Point

Temperatures range from -55°C to +47°C across the planet.

Dew point is calculated based on vapor presence using an inverse exponential model.

Max dew point spread is capped at ~21.5°C.

Relative Humidity

Derived using the Magnus-Tetens approximation: RH = exp((17.625 × Td)/(243.04 + Td)) / exp((17.625 × T)/(243.04 + T))

Turbulence and manual override scalars may apply.

Turbulence (Storm Potential)

Rossby wave interference simulates jet stream drift.

Turbulence ranges from 0 to ~1.0, typically peaking at midday.

Drives wind gusts and enhances storm formation.

Precipitation

Triggered when RH × Turbulence > 0.44 below mid-cloud level (~6.5 km).

Storm intensity scaled non-linearly into a 2–16 range.

Precipitation cools surface temperatures up to 6°C.

Average planetary precipitation coverage targets ~7.5%.

Wind Modeling

Wind direction is derived from directional map and stratified by altitude in 1 km layers up to 63 km.

Wind speed is a power function of source pixel value with turbulence-based enhancement.

Gust speed is scaled based on turbulence severity.

Altitude-based adjustments simulate realistic jet stream patterns.

Orographic Lifting and Visibility

Wind direction and speed determine an "upwind" terrain elevation lookup.

If upwind terrain is higher than current position, visibility is reduced due to fog from orographic lifting.

Orographic fog effect modulates with dew point spread.

Visibility Calculations

Visibility is computed by combining several factors:

Fog: When temperature-dewpoint spread < 0.2°C and upwind terrain is elevated.

Precipitation:

Light (2–6): reduces visibility to 2 km.
Moderate (10–12): reduces to 1–5 km.
Heavy (>12): reduces to 0.5–4.5 km.

Turbulence: Clears visibility under low precip conditions.

Wind Mixing:

5–15 m/s: improves visibility up to 2 km.
>20 m/s: dust/haze degrades visibility up to 1 km.

Final Clamp: Visibility is clamped to range 0.05–25 km.

Ceiling Calculations

Cloud ceiling is computed using: (T - Td) × 0.12192 km/°C

Adjusted for difference between surface elevation and upwind elevation.

Special adjustment for Deois city ensures minimum ceiling above highest structure.

If ceiling < 150 m AGL and altitude is below midcloud level, visibility is scaled down.

Sanity Checks and Final Conditions

Fog conditions force precip to 2.0 if visibility < 1 km.

Visibility and ceiling are synchronized to prevent unrealistic conditions.

Summary of Key Ranges

Temperature (Surface) -55°C +47°C Dew Point Spread 0°C ~21.5°C Precipitation 2.0 16.0 Wind Speed ~0 m/s ~83 m/s Visibility 0.05 km 25.0 km Ceiling (AGL) 0.0 km ~5.0+ km }

Notes

The system is designed for future expansion to include airborne radar, precipitation particles, and localized thunderstorm cells.

Orographic adjustments are dynamically computed at runtime based on directional wind sampling.

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