Polar night

Polar Night

The Polar Night is a phenomenon that occurs in the Polar Regions of the Earth during the winter months when the Sun does not rise above the horizon. This results in a period of darkness that can last for more than 24 hours, and in some cases, several weeks or even months.

Overview

The Polar Night occurs because the Earth's axis is tilted away from the Sun. This tilt, combined with the Earth's rotation, means that for a period of time, the Sun does not rise above the horizon in the Polar Regions. The length of the Polar Night depends on how far north or south you are. At the North Pole and South Pole, the Polar Night lasts for about six months.

Types of Polar Night

There are three types of Polar Night, each defined by how far below the horizon the Sun is:

• Civil Polar Night - The Sun is less than 6 degrees below the horizon. This means that there is still some light in the sky, and it is possible to see objects outside without artificial light.
• Nautical Polar Night - The Sun is between 6 and 12 degrees below the horizon. During this time, the sky is very dark, but the horizon is still visible due to the scattering of sunlight in the atmosphere.
• Astronomical Polar Night - The Sun is more than 18 degrees below the horizon. This is the darkest type of Polar Night, with no sunlight visible at all.

Effects on Wildlife and Humans

The Polar Night has significant effects on both wildlife and humans. Many animals, such as the polar bear and Arctic fox, have adapted to the extreme conditions of the Polar Night. For humans, the lack of sunlight can lead to Seasonal Affective Disorder (SAD) and other health issues.

See Also

• Midnight Sun
• Polar Day
• Polar Twilight