My personal favourite 'Clouds in Video Games': I used to play Quake 3/Quake Live competitively, and spent a lot of time in a small 'arena' map called 'Thunderstruck'[1]. The clouds in this map are absolutely ridiculous in terms of their realism, but there's something really nice about them. There's certainly no time in a Quake game to just sit and stare at the clouds, but they definitely add a bit of flavour!

1: https://www.youtube.com/watch?v=N6wwMSIWCWw