HI I just created my own texture pack and I replace the default game clouds.png to a another clouds.png which basic changes the cloud shapes and effect layers {SEE BELOW} and when i am playing in my desert world my render distance is at 8 - 12 and my own clouds.png but they is a line underneath at the end of the render cloud effect in my world.
This is working as intended; cloud, like blocks, have a render distance; the game is not going to process 60000000x60000000 blocks of clouds...