Photography corner: What is the “blue hour?”

According to Robert Testagrossa, in photography, there's something known as the "blue hour." Today's blog explains this term to help all new photographers take advantage of this.

So, what is the "blue hour," anyway? To understand it, you must first know that color is measured in degrees Kelvin (K), and that blue light has a higher K rating than other colors. Cooler temperatures exhibit more of this bluish hue, which means that during the daytime hours, objects appear bright-white or orange, compared to blue.

The "blue hour" happens after the sun has set and there is no natural light in the sky, which is why it's called a special time of day when there isn't much artificial light either (this also means that during this time of day, objects do not appear white or orange, but blue). During this time, the sky becomes slightly darker than it was during daytime hours and then there is a tint of blue in the air. This gives this time of day an ethereal and magical feeling and has been used for many years by photographers to shoot sunrises and sunsets.

Since we're talking about the "blue hour," you must be thinking, "I already knew this, what else is there?" Well, you're right. The term itself doesn't change much throughout different parts of the world- it's still considered to be a time when there isn't much light, and the sky looks blue (if not dark).

Robert Testagrossa explains that what does change is how long this period lasts: During winter months in northern locations, the blue hour can last for hours. In summer months however, it doesn't last as long, and this is because the sun sets later and therefore doesn't appear to stay in the sky as long since it's higher up and closer to the horizon.