The above two pictures almost reminds me of the storm clouds we get here in and around Lamphun.
Very immersive
It be interesting if there are any possiblities in creating a two toned massive cloud like dark on top and grey dark grey underneath.
Representing a massive storm rain front moving in.
Kirby
It is possible to create a two toned massive cloud like you mentioned but it will effect other weather conditions like Good, Hazy etc.
It means that flying in good weather will take place with dark grey clouds then. Which doesn't look very realistic.
Shape and colour of clouds look different in other parts of the world. Where I live clouds have a kind of light grey, silverish tone underneath. Probably because of reflection of water. And here we are surrounded by a lot of water so to say.
I try to achieve that same effect.
An ingame screenshot + inlay of an image of how clouds look like in my hometown.
I still have to fiddle out some things but haven't had much time to do so, I just got back from Paris and next week I'm in Madrid.
But release date will be September.
And after release you are free to edit the cloud.tga to make it as dark as you want to.
I gave it a quick try already and does it reminds you a bit of the massive storm front you have in Thailand?
A nice side effect is that with the huge clouds option set to low altitude it suggests rainshowers.