This is a continuation of this post. I promised a demonstration of how I layered together my colors, so here it is, rather sloppy and scribbly, but it should give you an idea of what it looks like.
This is just basic painting technique. In oil paints, I believe it’s called fat over lean, because your darks are a very thin layer of paint, while your lights are big chunks of it.
First, the reference pic:
First, some kind of warm, sunset background. Just a pink-to-gray gradient with some orange smeared over it, eyedropper-lifted out of the same area in the photo.
I see this particular cloud as kind of a loose pyramid. Here is that pyramid with big chunks of the darkest areas blocked in. I tried not to go for any detail at this stage. I just looked at the biggest, darkest areas in the cloud and put them in as big circles.
Building up some midtones now. This is where I started to flesh out the cloud’s actual shape.
Found I had some additional shapes in a shade between my midtone and my shadow, so I picked up a slightly darker purple and blocked those in.
Now for the second-brightest lights! This is the fun part, because it’s where the cloud really begins to pop. But the best highlights are built on a firm foundation of shadow, as some artist said who I can’t remember. The orange is eyedropper-lifted from the photo.
Notice that I’m starting to make my shapes and “puffies” smaller and smaller and more detailed. The eye goes to those bright areas first, because of the high contrast there, so you want to make the high contrast areas interesting.
And finally some touches of the very brightest color, a very light yellow.
This is far from done, because now you should go back and refine your dark areas, and make them puffy and cloud-like, always paying close attention to the shapes in your reference. My example is just a quick and dirty example of what dark-to-light painting looks like.