Enable clouds – Enables the cloud system.

Ground  shadows – When enabled, casts shadows from the clouds. See the Ground Shadows example below.

Improved shading – Enables more accurate shadowing of clouds by other clouds. Note that the results are better in offline rendering.

Density – Specifies the density of the cumulus and stratus types of clouds. A value of 100% fills up the sky with clouds. See the Density example below.

Variety – Specifies the variety of the cumulus and stratus types of clouds. See the Variety example below.

Cirrus amount – Specifies the amount of cirrus clouds in the sky. The maximum value of 1 fills the sky with cirrus clouds. When set to 0, the cirrus clouds are completely gone. See the Cirrus Amount example below.

Number of contrails – Specifies the number of airplane contrails visible in the sky. See the Number of Contrails example below.

Offset X – Moves the cloud system on the X axis.

Offset Y – Moves the cloud system on the Y axis.

Phase X – Specifies the phase by X axis, can be used to fine-tweak the cumulus and stratus clouds appearance. The appearance of the clouds loops at 0, 100, 200, etc.

Phase Y – Specifies the phase by Y axis, can be used to fine-tweak the cumulus and stratus clouds appearance. The appearance of the clouds loops at 0, 100, 200, etc.

Start height – Specifies the clouds staring height position. See the Start Height example below.

Thickness – Specifies the height of the cloud layer. Lower values make the cumulus and stratus types of clouds thin and sheer/lucent, while higher values make them full and heavy. See the Thickness example below.

Example: Density

The Density parameter controls the amount of clouds in the sky. The higher the value, the higher the amount of clouds appearing in the render. 

Example: Variety

This example shows how the Variety parameter affects the distribution and look of the clouds.

Example: Cirrus Amount

This example shows how increasing the Cirrus amount increases the appearance of the cirrus(high altitude, wispy) clouds in the render.

Example: Number of Contrails

Note that the contrails are spread randomly across the sky. In most cases, the camera does not capture all of the contrails.

Example: Start Height

Notice how the clouds change their position in the sky with increasing the Start height value.

Example: Thickness

The thickness parameter specifies how full the clouds are. Smaller values make them more thin and sheer, while higher values make them look heavy.