0 a night or the time in winter at places close to the North or South Pole, when the sun does not appear above the horizon -- 极夜
Each kind of polar night is defined as when it's darker than the corresponding kind of twilight.
The sun shines 24 hours in the summer, and barely ever shines at all in the winter (see midnight sun and polar night).
These areas either receive sunlight (midnight sun) or shade (polar night) 24 hours a day because of the earth's tilt.
Polar nights and the midnight sun may last months in this region, which has come to characterize the stereotype of the north.
The flora benefits from the long period of midnight sun, which compensates for the polar night.
That is the polar night.
A woman in the polar night.
Activity is at a stand-still during the polar night, which lasts for many months.
