Oregon Sunset (copywrite 2009)
There is more to painting clouds that just the brush to be used. Once you learn techniques you can use just about any type of brush you find comfortable. I have used a dry brush, angle, filbert, etc. to paint clouds. A lot depends on the type of cloud, the season of the year and the effect desired when choosing a brush type.
There is not just one type of cloud, and clouds are not just white any more than a sky is just blue.
I use my camera a lot to provide me with a scrapbook of examples and living in both OR and PA have provided me a lot of differences that are helpful.
I have found that my "best luck" has come from painting wet on wet. Painting in this manner allows you to mix and/or blend your colors and create soft edges easily. My mediums of choice are the
line of mediums by Brenda Harris. They are awesome. You do not want clouds that appear to be setting on top of your background color as I see so often. Soft edges and color mixes, as well as wet on wet allows you to not just paint a sky with white clouds; but clouds that reflect the rest of your design and seem to blend in with the sky. Through experimentation and practice you will be able to achieve many different looks. I also use a dry brush (as it is a bit stiffer) or if that doesn't work an artist signature brush
Maxines' Mop.
Use colors such as crimson, ochre, umbers, and different shades of blue to create and duplicate the beauty of nature. I especially like to use Paynes grey in a stormy sky for winter or rainy skies.
Use a color such as raw sienna, or burnt umber in your sky if you are using it in your main design in a house, barn, etc.
Also of importance is to remember perspective. Cloud formations are narrower, smaller and lighter the further away they are, or easier to remember: the closer they are to your horizon line.
Fade your edges out into a thinner, wispier line. Make your cloud formation smaller at the beginning and end.
My choice for brushes 9 times out of 10 is from one of the Dynasty lines of brushes. I love the quality, the way it feels in my hand, and the way it performs.
TYPES OF CLOUDS....
Cumulus: Strong winds seem to form these clouds so you want a lot of action when you paint working faster and a bit choppier. I like to do slipslap for this type of action sky. Random x strokes in different sizes and different directions.
Stratus: Sweeping, horizontal and long clouds which are more parallel...almost a ribbon like appearance.Cirrus: Clouds which are high in the atmosphere, feathery with a windswept appearance. Work lightly between brush and surface to get the wispy effect that suggests this type of cloud formation.With these clouds you may want to glaze a bit of red, orange or
ochre color to give just the suggestion of color. This can be done
using a transparent color and some of Brenda Harris' Clear medium as a mix.
Clouds are all about achieving "effect" rather than just painting a cloud in a blue sky. There are many elements to be considered. Just a brush choice is not the only choice in a successful, realistic
painting.
I love the color of new blue spruce evergreen pine needles. These look almost irridescent to me, and such a gorgeous, beautiful shade of blue green. 
