When you go to the beach or just sit in your backyard taking in the sun it's not really a hassle or strange to stare at the sky. Nobody will notice
it. Ok, last time i did it on a vacation i ended up with a bloody nose Still figuring out that one.
That is all fun and nice but you can test it for yourself.
Take a couple of clouds, pick the biggest one to dissipate, repeat with others and note the result. Dissipation occurs naturally, duh, ofcourse but
when you see that the biggest one in the group dissipates first every time you concentrate on it you can see a significant result. Normally the
smallest one dissipate first if and when it is in a dissipating state so to speak.
I don't think glass matters. Pick you a resonable sized one and either glare at the cloud while letting your eyes relax on it and keep the intention
in your thoughts. You can also scan the cloud in a grid pattern, works both ways.