I kept seeing this photo and imagining what colors I would use to capture the essence of that sky. Finally, I could resist no longer. I know there is no way that I can paint it the way God has with all of its rich color and varied shapes. But I can have fun trying! So here is my humble attempt. I did some small experiments with color and dropping in to wet areas. This would take some effort to do on a larger scale, as the areas have to remain wet as you work and the air is quite dry this time of year. But I still may give it a go.
I worked from top to bottom on a slightly tilted surface putting down pure color and always keeping the lower edge wet. You have to clean your brush thoroughly between colors or you will get mud. You also have to drop in your colors in a way that you do not have all three colors meet and mingle in one area. This also would produce mud. Do not let the edges of the wet blue and wet yellow meet directly or you will get a green sky. Lay down the reds and place your yellows inside these areas to avoid mixing with the blue.
After the initial sky was completely dry, I went back in with some blue in areas I wanted to strengthen. This gives more contrast and makes the pinks and yellows pop. You have to do this with a very light touch, because with strong color the pigment tends to lay on top of the paper and can be easily picked up if your brush is too wet.
For the poles and foreground, I really should have just mixed together the three primaries to get a dark that would be more harmonious with my painting. However, my puddles were too wet to apply a strong dark and I was impatient to finish, so I used sepia instead. If I paint it again, I will mix my dark from the sky colors as the shadows would reflect these.
Joy and blessings,