Version 1.6 : 
- compatibility with blender 3.x
- Installation issues fixed, no more need to run as admin

Version 1.5: (BE SURE TO INSTALL WITH BLENDER LAUNCHED IN ADMINISTRATOR MODE TO INSTALL ALL DEPENDENCIES) 

- 2.93 compatible
- initial moon support
- bugfixes

Version 1.4 is out :

-a new sky mode (cycles only) : you can now control the internal nishita sky texture and enhance it with all skysim features.
-2d clouds is now working in all sky models
-Preetham sun was too low, i increased the value so the sun disc is more visible.

version 1.3 is out, it add full eevee compatibility , creating godrays in eevee and cycles is faster than ever now, it also fix a few bugs with the groundfog density sticking to 0 sometimes. i recommand using bleder 2.83 with this version as it is optimized to use the new volumes render settings.

The new version is here with a new sky model :preetham. and it is now compatible with Eevee ! Just switch from nishita to preetham in the settings. Godrays creation is also simpler than before and is fully compatible with Eevee

Skysim is a sky and volumetric atmosphere addon for Blender.
what you'll get :
-Pure rayleigh sky shader that run on GPU
-2D and 3D Volumetric clouds layers
-Infinite ground layer
-Ground fog for atmospheric scattering
-Everything controlled in a single panel

It let you produce stunning atmospheres from sunrise to sunset without having to tweaks tons of settings.
It is based on the nishita osl sky shader and inspired by this article.
The sun disc rendering is based on the frostbite engine technique.
Just rotate the sun and the addon will make the perfect sky according to the sun position.
You can produce godrays in seconds and enhance your scenes with a real feeling with the volumetric fog.
you can add 2D and/or 3D clouds and animate the position of the sun, the clouds, almost everything.
It can be use to render outdoor ans indoor scenes, it's a full replacement for HDRI files, but it use only 1% of the memory of  HDRI ! (never goes over 50 Megas when HDRI's use Gigas !!) and is faster to render.

The goal is to achieve atmosphere photorealism.