Available Light
Available light is any light that exists in the scene naturally. This can be the sun in the sky or a neon sign. Just think of it as light that is already there, that you are not likely to be able to do anything to change.
Daylight
Daylight is the most common form of available light. It is also constantly changing. As the earth rotates around the sun, the available light changes from second to second. Each time of day has a different quality to the light.
Sunrise and sunset
Sunrise and sunset both have unique light properties. Because the sun is lower in the sky, the angle of the light creates long, low shadows that give depth to the scene. More importantly, the color of the light also changes at this time of day. Less white light is allowed to pass through the earth’s atmosphere, which gives everything more of a red or yellow hue. Photographers find this light highly desirable.
As the sun moves across the sky during the morning hours, the color temperature rises and the shadows get shorter. However, early morning is still a great time for landscape photography. The shadows are still long enough to create interest in your photos and the light is still soft with a yellow cast. The same is true of late afternoon.
Midday
When the sun is at its highest point during the day, the shadows are at their shortest, and any scene will seem flat. This is the worst time to photograph people outdoors. The light causes shadows to fall under the nose and eyes, which is the most unflattering way to photograph people. The light in the midday can be used for shooting, but most professional photographers prefer to shoot during the morning or the evening. If you do need to shoot people in the midday, use diffusers and reflectors to help modify the light. Shooting landscapes and buildings in the midday sun has the same set of problems. The angle of the sun causes small shadows with little texture. The image is likely to seem flat and dull, and the subject matter is too large to modify using diffusers or reflectors.
Electrical light
Artificial lighting runs the gamut from neon lights to streetlamps. The intensity of artificial light can vary greatly but doesn’t tend to fluctuate as much as daylight. A given type of light usually outputs the same color and amount of light over the life of the light source. Common artificial light types can be broken down into three distinct types: fluorescent, incandescent, and vapor discharge lights.
Fluorescent lights
Fluorescent lights have become the most common lights in workplaces due to their low power consumption. The light emitted from fluorescent bulbs can cause subjects to have a green cast.
When shooting in RAW, you can change and fine-tune the white balance on the computer after the photos have been taken.
Incandescent lights
Incandescent — or Tungsten — lamps used for photographic purposes have a constant color temperature of 3200 Kelvin, but common bulbs used in everyday lighting situations can vary in color temperature and usually have lower color temperatures, that is, they produce light with a redder color.
Vapor discharge lights
Mercury vapor, sodium vapor, and multivapor lamps have become very common in the world today and will render a subject a little greener than it ought to be. The light produced by vapor discharge lights is hard to accurately measure on the Kelvin scale and there is not a preset white balance setting for it.
Because this type of lighting is used in many places, it is likely to end up in your photographs at some point, so the best way to deal with it is to shoot using the RAW image quality. The image can then be adjusted later on the computer. If that is not an option, it is possible to set a custom white balance.
Mixed light
Mixed light occurs when a scene is lit by two or more light sources that have different color temperatures. The human eye can deal with mixed lighting automatically, but the camera sensor cannot. The camera needs to have the white balance set so that the colors are reproduced correctly, but what do you do when there are two or more different color temperatures in the scene? For example, if you are shooting an indoor scene that has light from both a window and an indoor lamp, you must choose a white balance carefully. But, how do you know which light source to choose for? One strategy when shooting in mixed light is to leave the white balance set to AWB (auto white balance) and use the color of the light to create a mood in the photograph. A second strategy when shooting in mixed light, is to shoot the image as a RAW file and color-correct the file later using software.
Have a look at other articles describing the influence of lighting conditions on photography:
The Color of Light, The Diffusion of Light, The Intensity of Light, Light Direction,