Introducing colour :

I worked on the sky and clouds,using glazes of the same colours of the underpainting(unltramarine,cobalt blue,white and paynes grey).The clouds highlights were warmed up a bit with some tiny bits of yellow ochre and orange.A mixture of magenta and ultramarine was also introduced into the clouds shadows.

Then I moved down to the landscape,working from background to foreground,doing my best to create the illusion of depth and reinforce the effect of the atmosphere.I also made sure not to lose the contrast of light and shadow on the valley which I already had on my underpainting