For a recent project I found I needed to create some realistic looking clouds in the background of an illustration, but I had to keep the whole thing in Illustrator. Moving to Photoshop wasn't an option as the image could potentially be used at any size, from 10cm wide to two-feet wide or more, so vector format was the order of the day.
A quick search online for "realistic clouds in Illustrator" threw up plenty of results, but none that would give the effect I was looking for. Most seemed to rely on using gradient meshes or symbols, custom brushes and the like. After a little experimentation I found a solution that worked well, and I've since used for a couple of other projects, so I thought I'd document it in case anyone else might find it useful.
This is my first stab at a tutorial, so hopefully it all makes sense outside my head. If people do find it at all useful then maybe I'll post some other tips and tricks.
1. In Illustrator create a new document (File > New), draw a rectangle to cover the background and then draw an oval as the base for your cloud.
2. Apply the Feather effect (Effect > Stylise > Feather).
3. Apply the Scribble effect (Effect > Stylise > Scribble). Some of the preset settings can be a good starting point to get the cloud shape you're looking for.
4. Apply the Gaussian Blur effect (Effect > Blur > Gaussian Blur).
5. At this point it's probably not looking too good, now that all the effects are applied we can tweak them to get a better looking effect. To edit an effect that's already applied select the shape on the artboard and double click the effect you'd like to edit in the Apearance Palette.
That's a bit more like it!
6. One cloud on its own looks a bit lonely so you're probably going to want to duplicate it and resize/reposition. Alternatively, once you have a basic cloud with all the effects in place you can drag it to the Graphic Styles palette to create a style that can be applied to any other shape/object in one click.
Simon took our initial concept to very loose script and created a list of illustrations we needed to make our whiteboard video simply work. He delivered the first few illustrations in sketch form, and we knew he was going to nail it. On budget and on time every step of the way, Simon was not only a genius illustrator but a lovely person to work with. He has a talent for taking the everyday and making it sing. He delighted our audience with his clever and cute characters, and went beyond what we thought was even possible. We'd work with him again in a heartbeat. Jennifer del Greco, pndu.org