Weather

Weather on Vieneo affects visibility, flight conditions and surface operations. Moisture, convection, terrain and atmospheric circulation produce extensive cloud cover, storm belts, gusts and fog.

Overview

Vieneo is a tidally locked exomoon with a dense, high-pressure atmosphere and perpetual cloud cover. Temperature, humidity, terrain, wind and time of day interact to produce changing local conditions. Check conditions along the route as well as at departure and destination.

Atmospheric Characteristics

• Atmospheric Pressure: ~2.6 bar at sea level
• Diurnal Cycle: 14.43-hour day
• Peak Temperature Lag: ~3.5 hours after local solar noon (≈87.3° longitude offset)
• Midday Temperature Rise: Typically less than 10°C due to dense cloud cover

Measured Global Averages

• Turbulence: Avg 0.358 (scale 0–1)
  • Peak turbulence occurs near equatorial storm zones, with transient strong updrafts.
• Relative Humidity (RH): Avg 58.2%
  • Min: 18.3%, Max: 100%
• Precipitation: Varies by moisture and convection; see Precipitation for the reporting index.
• Wind Speeds:
  • Avg: 4.71 m/s (~10.5 mph)
  • Max observed: 56.4 m/s (~126 mph)
  • Area with >20 m/s winds: 0.4%
• Visibility:
  • Avg: 40.1 km
  • <1 km: 2.0%
  • <5 km: 3.5%
  • <10 km: 3.6%
  • >30 km: 94.5%

Flight Rules Classification (Ceiling AGL and Visibility)

• Instrument Flight Rules (IFR): 7.4%
• Marginal VFR (MVFR): 47.6%
• Average Ceiling: 1.16 km AGL (~3,800 ft)

Diurnal and Seasonal Effects

• Temperature modulates with solar angle
• Seasonal subsolar movement causes ±10–12°C swings

Temperature and Dew Point

• Range: -55°C to +47°C
• Dew point depends on humidity and temperature
• Max dew point spread: ~21.5°C

Relative Humidity

Regional humidity changes with moisture circulation, convection and daytime drying. Dew point depends on humidity and temperature. A regional humidity reading does not describe every altitude within a cloud tower.

Turbulence (Storm Potential)

• Jet streams drift in wave patterns
• Daily peak near midday
• Affects gusts, cloud formation, and precipitation
• Dense air and strong convection can produce widespread turbulence

Cloud forms above the deck

Regional cloud tops range from approximately 10 to 22 km MSL. The cloud deck remains present beneath the lower tops; low cloud-top height does not mean clear sky.

The connected cloud sheet rises and falls with regional conditions. Rounded billows, wind-shaped streaks and uneven relief give it local texture; the cloud surface is not a flat ceiling at one altitude.

Cloud height alone does not indicate rainfall intensity or turbulence. Use weather observations and Weather Radar alongside the view outside. Cloud lightning can illuminate the cloud bodies from within.

Precipitation

• Precipitation depends on moisture and convection together. Storm potential is adjusted relative humidity multiplied by convection; lift potential alone does not imply rain.
• Rain can occur below 10 km MSL where moisture and convection are sufficient. Cloud formations can occur without precipitation.
• The precipitation index ranges from 2 (no-storm baseline) to 16. It is not a direct rainfall rate in mm/hr; precipitation classification treats values below 2.5 as none.
• Rain cooling can lower the temperature by up to 6°C.

Winds aloft

• Layered up to 63 km altitude
• Gusts enhanced by turbulence
• Strongest winds seen in mid-latitude and equatorial storm belts

Orographic Lifting and Visibility

• Visibility reduced when upwind terrain is higher and RH is high
• Modulated by dew point spread and wind speed

Visibility

• Fog: Triggered by small T–Td delta and elevated terrain
• Precipitation visibility effects:
  • Light (2–6): ~2 km visibility
  • Moderate (10–12): ~1–5 km
  • Heavy (>12): ~0.5–4.5 km
• Wind Mixing:
  • 5–15 m/s: improves visibility
  • >20 m/s: can cause haze and dust
• Visibility range: 0.05–25 km

Cloud ceiling

• Formula: (T - Td) × 0.12192 km/°C
• Adjusted for terrain height difference

• If ceiling <150 m AGL below midcloud, visibility is reduced

Notes to Pilots

• Cloud Bases: Widespread stratiform decks, often 1–2 km AGL
• Low Visibility Zones: Mountainous or humid regions prone to IFR
• Storm Zones: Mostly near equator or mid-latitudes
• Winds Aloft: Expect wind shear near jet streams
• Turbulence: Persistent turbulence and strong convection are common

Cloud lightning

Above the clouds, lightning appears as brief illumination scattered through existing cloud moisture. Sources follow the occupied cloud bodies, including raised convective billows. A discharge can illuminate one to three connected sections in sequence, with irregular repeat pulses; exposed bolts are not required to see this orbital effect. Look down toward active storms, preferably at night or twilight. Flashes have less contrast against directly sunlit clouds and remain easier to see in darker cloud regions. This depends on the illumination at the clouds, not simply whether the ship is on the day or night side.

Lightning is distributed across the moon and is concentrated in active cloud regions. Only a portion is visible from any one vehicle: the horizon, viewing direction and intervening clouds limit the view. Connected flashes and repeat pulses can belong to the same discharge.

The flight simulator does not reproduce cloud lightning.

Summary of Key Ranges

Parameter	Min	Max
Temperature (Surface)	-55°C	+47°C
Dew Point Spread	0°C	~21.5°C
Precipitation index	2 (no-storm baseline)	16
Wind Speed	~0 m/s	~60 m/s
Visibility	0.05 km	25.0 km
Ceiling (AGL)	0.0 km	~5.0+ km

Imagery

Global weather radar map showing precipitation clusters

See Also

• Atmosphere
• Player Portal

• Doppler Radar