Photographers always talk about lighting. The lighting in a photograph is so important that many will wake up at the crack of dawn to take a particular picture, others will wait until dusk. The lighting affects the mood the photographer wants to portray in his picture. Good lighting can be the difference between an okay photo and a spectacular one. Photoshop and other software editing tools have become so popular partly because photographers can use them to manipulate the lighting in their photographs. They can doctor up photos in which the light might not have been very favorable. Like photographers using Photoshop, writers can doctor up their scenes with the right light.
As writers I think it is important to cast our story in the correct light. We're used to having light describe in phrases such as, "Sara entered the pitch black hallway," or "The light temporarily blinded Tom as he walked outside". Description is a common way we use light in our stories.
Descriptions of light can be used to establish a scene. "Darkness descended onto the crash site. Quickly, flood lights were set up to illuminate the area in which rescue crews were diligently searching for more survivors." The light tells you the time of day or the tansition of time, from day to night.
Light can also be used to provide insight about our characters. "The morning light slowly crept across the room returning warmth to the occupants of the small house," or "The darkness enveloped him except for a sliver of moonlight that illuminated the angry scar on his right cheek".
What about using light to set the mood? Movies do this all the time with darkening skies or glorious sunrises. How do you light up your stories?