Understanding how natural light works is a major topic of discussion during my digital photography classes. Since photographing sunsets and sunrises is a popular activity for travel photography, I typically try to explain how sunlight interacts with the atmosphere to create some stunning effects.
In addition to discussing the concept of the “golden hour”, which is the first and last hour of sunlight in a given day, twilight also plays an important role in outdoor photography. Most people are familiar with the term twilight, but many are unaware of the different types of twilight. According to the National Oceanic and Atmospheric Administration, twilight occurs in three phases and occurs during both sunrise and sunset:
- Astronomical Twilight: the time at which the sun is 18 degrees below the horizon. It is that point in time at which the sun starts lightening the sky. Prior to this time during the morning, the sky is completely dark. During the evening, this is the point where the sky completely turns dark.
- Nautical Twilight: the time when the center of the sun is 12 degrees below the horizon, and only general or vague outlines of objects are visible. During the evening this is when it becomes too difficult to perceive the horizon, and in the morning this is the point when the horizon becomes distinguishable. This term goes back to the days when sailing ships navigated by using the stars.
- Civil Twilight: the time at which the sun is 6 degrees below the horizon. At this time, there is enough light for objects to be clearly distinguishable and that outdoor activities can commence (dawn) or end (dusk) without artificial illumination. Civil twilight is the definition of twilight most widely used by the general public.
To demonstrate the twilight effect, I photographed the morning sky behind my home.
While these images were taken only moments apart, the color of the sky and clouds is quite different. This is due to the fact that the sun was moving through the phases of twilight, altering the angle at which light hit the atmosphere. As this angle changed, so did the color of the light.
When capturing images during the early and late day, consider shooting before sunrise and after sunset for some great color opportunities.