Precipitation and Obscuration

Weather type	Description	Caused by	Effects
Haze	Obscuration Light atmospheric dust
Dust	Obscuration Denser, often abrasive, atmospheric dust		Hover: 5% speed penalty VTOL: 10% speed penalty
Mist	Obscuration Light fog reducing visibility to 1 – 3km		Visibility reduced, but still above 1km, at low altitudes.
Fog	Obscuration Dense fog reducing visibility to 0.1 – 1km.		Significantly impairs visibility to less than 1km, sometimes down to lower than 180m, at low and medium altitudes. Hover: 5% speed penalty VTOL: 5% speed penalty
Drizzle	Precipitation Water droplets below 0.5mm diameter, almost mist-like.	St, Sc str op	VTOL: 1% speed penalty
Rain	Precipitation Water droplets above 0.5mm diameter.	As, Ns, Ac flo, Ac cas, Cu con, Cb Ice from Ci or Cs may trigger rain formation in lower clouds.	VTOL: 5% speed penalty Wheeled: 5% speed penalty Halt-tracks: 2% speed penalty Burn duration reduced by 25%
Lightning	Electrical discharge between earth and clouds (fork lightning), or between or within clouds (sheet lightning).	Cb, Ac flo, Ac cas	Inflicts thermal damage if it hits a building, VTOL or hovercraft. Inflicts EMP damage if it hits any other propulsion type. Sensor range reduced by 10% Disables minimap for 3 seconds if it hits HQ.
Snow	Precipitation Clusters of ice crystals.	As, Ns, Sc str op, Cb	Burn damage reduced by 25% VTOL: 2% penalty Wheeled: 10% penalty Half-tracks: 2% penalty
Blizzard	Precipitation Dense snowfall often with gusty winds. Significantly reduces visibility.	As, Ns, Sc str op, Cb	ROF reduced by 10% Burn duration reduced by 10% Burn damage reduced by 25%
Hailstone	Precipitation Solid lumps of ice.	Cb, Ac flo, Ac cas	Burn damage reduced by 10%

Other types of precipitation not implemented (and do not intend to implement):

Diamond dust – minute ice crystals that only occur under very cold and frigid conditions.
Freezing rain – rain tat freezes on impact to create a shiny glaze.
Ice pellets – clear ice, below 5mm (frozen raindrops)
Sleet – melting snowflakes or a mixture of snow and rain
Small hail – snow pellets with a thin ice coating
Snow grains – opaque, flattened ice grains below 1mm diameter
Snow pellets – opaque ice grains between 2 – 5mm

Fog

"A summer fog for fair,
A winter fog for rain.
A fact most everywhere,
In valley or on plain."

Fog is formed when the air cools enough that the vapor pressure encourages condensation over evaporation. In order for the air to be cool on a summer night, the sky must be clear, so excess heat can be radiated into space. Cloudy skies act like a blanket, absorbing and reradiating the heat, keeping it in. So if it is cool enough (and clear enough) for fog to form, it will probably be clear the next day. Winter fog is the result of two entirely different circumstances. Above the ocean or a large lake, air is typically more humid than above land. When the humid air moves over cold land, it will form fog and precipitation. (To the east of the North American Great Lakes, this is a common phenomenon, and is known as the "lake effect"). In northerly climates, ice fog may form when the temperature drops substantially below freezing. It is almost exclusively an urban phenomenon, when the air is so cold that any vapor pressure results in condensation, and additional vapor emitted by automobiles, household furnaces, and industrial plants simply accumulates as fog.