Our sun is the single light source that illuminates the earth, yet with the help of the atmosphere and a constantly changing pattern of clouds and weather, it creates an infinite variety of lighting conditions. The greatest variation occurs in the direction, quality and color of sunlight. These, in turn, depend mainly on three things: the season, time of day and the weather.
No studio can reproduce all the variations of natural light, and it is these variations that give outdoor photography so much of its surprise and unpredictability. This said, one useful way of appreciating the variables is to think of an outdoor location as an enormous, natural studio set. The earth's atmosphere acts partly as a diffusing screen for the sun and partly as a large reflector (a little light is reflected back from the ground, more from snow, sand and other bright surfaces). Finally, a constantly changing screen of clouds and suspended particles function as a complex array of filters.
