Installation instructions for The Reach:

These instructions are for installing the planet pack The Reach 1.1, currently for KSP version 1.8.1
The Reach is not meant to be used with other planet mods, nor tested to work with those. Use of other planet/system mods is at your own risk.

1 - Drag and drop the "The Reach" folder to your "KerbalSpaceProgram/GameData" folder.
2 - Download and install Kopernicus - https://github.com/Kopernicus/Kopernicus/releases/download/release-1.7.1-4/Kopernicus-1.7.1-4.zip
3 - [OPTIONAL] Download and install Scatterer - https://github.com/LGhassen/Scatterer/releases/download/0.053/Scatterer0.053.zip
4 - [OPTIONAL] Download and install EVE - https://github.com/WazWaz/EnvironmentalVisualEnhancements/releases/download/EVE-1.4.2-2/EnvironmentalVisualEnhancements-1.4.2.2.zip
5 - [OPTIONAL] Download and install Sigma skybox replacements - https://github.com/Sigma88/Sigma-Replacements/releases/tag/B_v0.5.1
6 - Enjoy, or else...

6 - Present in the GameData/TheReach/EVE/Atmosphere/Textures folder are two variants for the clouds of Liquen; a swirly one, and the rough one.
To use the swirly edition, simply rename the file Liquen2.png to Liquen1.png, and make sure the original Liquen1.png has a different name.