Glare (look) occurs when someone is displeased with another person. Glares can be passive, and are sometimes unnoticed by the party for which they are intended. Some societies, like the Congo, use Glares as a means to communicate long distances.
Glare (science) is also found when the sun shines brightly over a reflective surface. Science Glare can be dangerous if you're driving towards a lake or on a sheet of sunny ice. The best way to reduce Science Glare is to wear sunglasses or close your eyes.