Here are the concepts I've shown in the class lessons.

Choosing blues for your sky - I usually have Ultramarine, Cobalt and Cerulean Blue in my palette:

Here are some gradient washes for simple skies:

Mixing any blue with Burnt Sienna (or other earth colors like Burnt Umber, Indian Red, Yellow Ochre) can give you interesting color variants for skies and cloud shadows. Granulating pigments will produce granulating washes:

For painting white clouds you can paint around the cloud with blue, let it dry and add the shadow (top). Or you start with the shadow and add the sky later (bottom). Either way, you show the cloud by leaving the paper white.

Painting fluffy good weather clouds:

Painting airy clouds by lifting color:

Painting rainy clouds:

Painting a sunset with a gradient:

Painting a pink sunrise:

Painting a thunderstorm wet into wet:

I hope you enjoyed all the lessons! Leave a review to let me know what was most useful to you. :-)

Now it's your turn - enjoy painting and watching the clouds drift by!