I started painting the sky with the clouds using a very rough brush. As image evloved, I realized that I was going for an almost 3D type of realism in my 2D piece. So I separated the clouds from the Bg, and smoothed the BG with soft wide brushes and graidients.
As for the fumes, I used the same brush on and off - which was a clligraphy brush with adjusted settings, also I used a cloud brush of “Wacom brushes”, and another brush I created within PhotoShop. Along with some smudging and liquify effect.
I was thinking about it, and now decided after your question: As soon as I get a chance, I’ll post all the brushes that I’ve painted this image with. They really worked for me, and hope they may be useful for others too…