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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. The descriptions below are based on relatively clear skies, so the sky will be darker in the presence of dense clouds.
Noctilucent clouds during arctic dawn seen from high altitude. Data from the Aeronomy of Ice in the Mesosphere satellite suggests that noctilucent clouds require water vapour, dust, and very cold temperatures to form. [9] The sources of both the dust and the water vapour in the upper atmosphere are not known with certainty.
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
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 ...
Falling diamond dust (Inari, Finland) Diamond dust is similar to fog in that it is a cloud based at the surface; however, it differs from fog in two main ways. Generally fog refers to a cloud composed of liquid water (the term ice fog usually refers to a fog that formed as liquid water and then froze, and frequently seems to occur in valleys with airborne pollution such as Fairbanks, Alaska ...
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 ...
As a result, the cloud base can vary from a very light to very dark grey depending on the cloud's thickness and how much light is being reflected or transmitted back to the observer. Thin clouds may look white or appear to have acquired the color of their environment or background. High tropospheric and non-tropospheric clouds appear mostly ...
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.