Clouds formed like clouds ?

Hi,

currently i have a dome (basically a half sphere modelled in maya) imported in the scene. On that i render some perlin noise heaps , but they dont seem like clouds (see first picture)

Basically i want it to be like the one in the second picture (only that it forms clouds like that not with the iliminated edges only the shape i want to achieve)

can someone give me tips on how to do that in the shader.

The shader is from unisky at the asset store.

first picture

second picture (link) : link text