Because you can get them right here. Created by SLer Stevie Davros, who says "[t]hese clouds will slowly scroll across the sky like the regular ones, but the shapes are fixed." These exist because Davros was recently experimenting with (really fantastic-looking) realistic skies. "Whilst tinkering," he says, "I came upon the idea of going for the opposite - cartoon=look clouds. So I made a few cloud TGA files and tweaked sky settings to work with them. Version 1 clouds are 1024x1024 and the res was not ideal, so I pushed the envelope and made a 2048x2048 TGA for cloud style 2." More about his naturalistic virtual clouds soon (hopefully), but meantime here's his cartoonified clouds to play with.