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The length of polar night varies by latitude from 24 hours just inside the polar circles to 179 days at the poles. As there are various kinds of twilight, there also exist various kinds of polar twilight that progress towards true polar night. Each kind of polar night is defined as when it is darker than the corresponding kind of twilight.
Olbers's paradox says that because the night sky is dark, at least one of these three assumptions must be false. Olbers's paradox , also known as the dark night paradox or Olbers and Cheseaux's paradox , is an argument in astrophysics and physical cosmology that says the darkness of the night sky conflicts with the assumption of an infinite and ...
Relationship of Earth's axial tilt (ε) to the tropical and polar circles. The Arctic Circle is the southernmost latitude in the Northern Hemisphere at which the centre of the Sun can remain continuously above or below the horizon for twenty-four hours; as a result, at least once each year at any location within the Arctic Circle the centre of the Sun is visible at local midnight, and at least ...
A map of the Arctic. The red line is the 10 °C isotherm in July, commonly used to define the Arctic region; also shown is the Arctic Circle. The white area shows the average minimum extent of sea ice in summer as of 1975. [1] The climate of the Arctic is characterized by long, cold winters
An arctic blast will send temperatures across the United States plummeting as bitterly cold air that originated in Siberia will arrive from Canada by week’s end, bringing with it dangerously ...
The Milky Way is brighter in the Southern Hemisphere than in the North. (Photo taken at La Silla Observatory) [2]. The fact that the sky is not completely dark at night, even in the absence of moonlight and city lights, can be easily observed, since if the sky were absolutely dark, one would not be able to see the silhouette of an object against the sky.
Here's a breakdown of how and why it all happens. But the science behind a blue sky isn't that easy. For starters, it involves something called the Rayleigh effect, or Rayleigh scattering.
"The Arctic air coming through Jan. 15th can be the coldest of the winter so far," Anderson said. "This batch of Arctic air will have a vast zone for fresh snow cover to work with and a direct ...