Strong light doesn’t usually come from below a face, so when you see it, it grabs your attention. We tend to associate it with firelight or theatrical footlights, which can suggest a magical, sinister, or dramatic feeling.
We hardly recognize family, friends, and celebrities when we see them with the light shining upward on their features.
Sources of light that shine upward are often strongly colored, either with the warm orange glow of firelight, or with the blue flicker of a computer screen.
The portrait of the character Lee Crabb from Dinotopia, below, shows him at a dramatic moment when he wants to take control of a powerful glowing sunstone. The ruby-colored light from the sunstone gives him a threatening, power-mad look. The underlighting is combined with a strong, cool edge light from the right.
Not all upward light arrangements suggest drama or evil. A person relaxing with a sun-flooded book might have her face lit mainly by the reflected light, which would have positive connotations.