Many painters put a blue tinge into shadows on sunny days in their paintings. If it's done in the right amount, it can make the image more visually deep. Some of it depends on the feeling you want to invoke.
For portraits, I like warmth, generally. But I can imagine having a very serious-faced portrait where you'd want to emphasize the coldness. Just an example. My father has a very serious-mood painted portrait in his home which is entirely painted with blue, black, and white.
For portraits, I like warmth, generally. But I can imagine having a very serious-faced portrait where you'd want to emphasize the coldness. Just an example. My father has a very serious-mood painted portrait in his home which is entirely painted with blue, black, and white.