M_Sky_Panning_Clouds2 - but transparent?

Hi guys,

I’m using the M_Sky_Panning_Clouds2 material to create a cloud layer on my sky sphere. Unfortunately the sun disk disappears completely behind the clouds and the clouds have pretty sharp edges. I’d like to get rid of these effects and have the sun shine through the clouds.

Any idea how to achieve that? Or is there a better procedural cloud material somewhere (maybe even for free)?

//edit: see this screenshot. The rising sun disappears behind… something… the cloud layer probably.