Wet on wet I painted the sky with a mix of cobalt teal and cerulean blue, concentrating the most color in the center. Then I painted some low lying clouds while still wet with a violet mix of cerulean and permanent rose. I carried this below the mountain line.
While the paper was still wet, I added some distant trees with a strong mix of cerulean and maroon perylene. Don't make it too strong that it is very dark....remember the atmospheric conditions are cloudy and you wouldn't see it so dark, but by keeping less water on your brush you can keep the paint from spreading too much.
There are also some green distant trees that I added with sap green and a little cerulean blue.
I let the paper dry and then added the rest of the background trees, being careful not to get too detailed and let the colors mix.....I wanted it to appear foggy. The rusty color is alizarin and burnt sienna with a little cobalt in it. I also used a violet with with the same colors except more cobalt and less burnt sienna. The darker violet I used ultramarine instead of the cobalt. The pine trees are sap green with a little cadmium red. I added some cobalt to shade one side.