I've responded to your PM. Thanks for confirming you cannot inject clouds live in Skyforce. Yes I have used the mini-app in EF to tweak the colours and sizes of the clouds but I am underwhelmed by the results. I have PM'd you about this. Best Regards,

For anyone else having trouble understanding Skyforce and Environment Force, SF cannot inject clouds while the sim is running so you can see the results. But if you build a theme of clouds and sky you can "install" it then with the sim running open Environment Force and perform quite radical tweaks on the look of the weather, then save that as a theme within EF. Once you've got used to it, it works quite well. Many thanks to vcarlo for taking me through the required steps.