Most stunning landscape photographs are either taken at sunrise or at sunset. Why is this?
What do you like most about the sunset? Is it the great variety of colours in the sky? Or is the how the whole world seems to slow down a bit? It is all related to the light at that moment.
To understand this page, it is import to know that sunlight has seven colours (the rainbow is proof of this): red, orange, yellow, green, blue, violet and indigo. The further light travels trough the atmosphere, the more spread out the blue lights are. Because the blue lights are spread out, the red lights are more visible. It is also necessary to understand that the night is only black because the lack of light. It is actually deep blue.
Twilight is the transition between day and night (and vice versa) and happens in multiple phases. It starts deep in the night, the sky is black. A few hours before sunrise, the sky slowly starts to get a bit brighter. Pitch black darkness turns into deep blue. At this point, the sun is still far away from the horizon (at another part of our planet), but she is getting closer. Just enough light travels trough the atmosphere to light up the sky a bit. This is called astronomical twilight. A little moment later, the sun is getting closer to the horizon, the sky turns blue and is bright enough to see the shapes of the world around you. This phase is the nautical twilight.
Moments later, as the sun is getting even closer to the horizon, the light still has to travel a far distance, but is bright enough the wake the world up. It is the civil twilight. The sun is just starting to peak around the bulging edge of the planet to reach the part of earth where day is about to start. Like mentioned, when light has to travel far, the blue lights spread out and the red lights are more visible. As a result, with the right conditions, just when the sunrise starts, the sky is turning red. The best change for a red sunrise, is when there is approximately 70 percent overcast. Too much clouds block out the sunlight, too little clouds and the light has no objects to reflect on.
After the civil twilight, rises over the horizon, and as it gets higher in the sky, the blue and red colours are mingled again, combining for white bright daylight.
The phases described are shown in the image below during a sunset.
During sunrise, night turns to day in the phases astronomical twilight, nautical twilight, and finished by civil twilight. The sunset is during the civil twilight. However, when day turns to night, these phases take place in reverse order: day becomes the civil twilight at sunset, and turns into nautical twilight, and after the astronomical twilight day becomes night.
When night turns to day, or day turns to night, during the astronomical twilight, there are approximately 40 minutes when the sky is blue and the world becomes a little visible. These 40 minutes, are called the blue hour.
The blue hour is a beautiful moment to take pictures. The orange lights in the city are still shining, and are in great contrast with the blue sky (complementary colours).
This page shows the time when the blue hour starts at a any given location: BlueHourSite.
Just before, during, and a little after sunrise, there is a moment (approximately one hour) that is called the golden hour. There is a second golden hour on a day, just before and during sunset.
A camera can only capture a marginal bandwidth of difference in light intensity. When the sun reaches a higher position, the light beams hit the earth directly. The light is intense, and the shadows are a bit darker. The difference in light intensity between shadows an sunny parts of a scene is high, something what a camera can’t handle.
So why is this moment called the “golden hour”? As explained above, during civil twilight, light has to travel a far distance. Because light has to travel far, the blue lights are spread out and there is more room for red light. This gives the light a golden glow and the moment roughly lasts one hour! Of course, during the winter, the sun is much lower at the horizon than in the summer, hence the golden hour lasts a little longer.
During the golden hour, most light is indirect, and therefore less intense. Less intense light means less harsh shadows, and this means: softer pictures!
This website shows when the golden hour starts and ends at a certain location: Golden Hour.
On sunny days, the light is prettiest during sunrise and sunset, and a bit harsh during the day. But when there is more than (approximately) 80 percent clouds, the clouds block out sunlight and the effect of the golden hour is nullified. This (usually) means: no gorgeous sunset or sunrise.
However, on these cloudy days, the light will be subtle as long there is overcast. This is because the clouds block the sunlight and spread it out. This is called diffuse light. You can reproduce this by shining a flash-light on the wall. The light is very bright on the wall. Now hold a piece of white paper a few centimeters in front of the flash-light. The light is much softer now, also know as diffuse!
So if you wake up early to shoot the sunrise and the clouds spoil your fun, do not get upset, just change your game plan and use the clouds to your advantage.