In "The Scream", Edvard Munch uses warm colors such as reds and oranges for the upper part of the sky. For the lower parts, he uses cool colors such as blacks and blues. His color choices make the artwork come together.
As for line, Munch uses curvy, wavy-like lines to create the sky. If you examine the sky, you can see that the paint (or whatever material he used) is wavy-like. The Scream itself is created with curvy lines (you can see this by its hands and the way the chin and body are curved).
