Procedural Skies is a currently work in progress update. They are clouds that can be inserted in to 
Terrain.
It has got 3 phases: 1, 2, and 3.
- Phase 1a has Clouds integrate with the
Sky object, and optionally act in composition with the Atmosphere object. - Phase 1b is in progress now and aims to gather performance stats, bug reports, and feature requests from developers, iterating based on that feedback.
- Phase 1c will offer an alternative for completely physically based Clouds and Atmosphere without a need for the Sky object's skybox cubemap textures, aiming towards better ultimate realism. Current Sky controls will remain for various skybox use cases.
In all stages of Phase 1, wind has a suitable fixed default motion and a preset animated cloud motion is released for this early ‘open beta’ phase.
Phases 2 and 3 will extend features to allow flying through and above clouds, with further lighting improvements and controls for cloud types and shapes.
The volume of Clouds extends to the horizon and includes a visual curvature to extend down to the horizon. This is a default behavior in Phase 1a. Later on, further controls will be developed and released.
The Clouds object appears in Studio under the Terrain object, which is a child of the 
Workspace service. The Clouds object contains a collection of clouds across the sky. Initially, only one Clouds object is rendered to cover the whole sky.