The second rollout on the Environment tab is Weather, three parameter settings are included: cloud, fog and wind.
Cloud
The parametric cloud system is used in conjunction with the geographic sky system to freely control the effect of clouds in the sky.
Amount: Controls the area and volume of clouds in the sky. The higher the value, the more clouds there are and the thicker the cloud layer.
Speed: Control the speed of the cloud. Note that you have to turn on "Realtime" in the "Display mode" in the upper right corner of the viewport to preview the cloud movement.
The higher the value, the faster the cloud is moving.
Direction: Control the forward direction of the cloud, the control value range is 0°-360°, when previewing, please make sure the cloud has a certain initial movement speed, and turn on the "Realtime" display mode.
Note: Cloud parameters do not support video shot keyframes. In each video clip, the cloud effect always follows the cloud parameters set in the first shot.
Fog
Control the fog effect in the scene to add realism and depth to the scene.
Color: Click the color slot to open the color picker and change the color of the fog. When the color is warm, it will produce a desert-like, smog effect. When the color is cooler, it will produce a water vapor-like effect.
Density: Controls how dense the fog effect is. The higher the value, the thicker the fog.
Volume Light: Light is scattered by particles in the air, making light paths visible. This effect is also often referred to as "God Ray". Turning on this option will increase GPU memory consumption.
Scattering: Controls the distribution of the volume light scattering effect. The default value of 0 makes the fog uniformly bright, and adjusting it to 1 makes the fog from the direction of the light source brighter.
Turning on Volume Light option will increase GPU memory consumption.
Wind
Strength: Control the wind movement effect of the plant. The higher the value, the more obvious the wind-driven effect.
Strength: 0.3
Strength: 0.5
Direction: Freely change the wind direction, the control value range is 0°-360°.
Please turn on "Realtime" in the display mode to preview the wind effect.
Precipitation( Rain and Snow)
Precipitation Contains snow and rain system , with adjustable strength and ponding parameters.
rain and snow parameters ：Switch weather effects and transition states through the Rain and Snow slide bar. The precipitation velocity gets higher when the value is closer to both ends.
strength：We can adjust the Strength parameter to control the size and density of raindrops or snowflakes in the sky, from light drizzle to full-blown downpour, from winter flurry to whiteout blizzard, or even sleet if you want.
ponding：Ponding parameter is to control the degree of the ground affected by precipitation. The greater the value, the greater the ponding or snow on the ground. There is no ponding or snow when the value is 0.