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Noctilucent clouds are composed of tiny crystals of water ice up to 100 nm in diameter [4] and exist at a height of about 76 to 85 km (249,000 to 279,000 ft), [5] higher than any other clouds in Earth's atmosphere. [6] Clouds in the Earth's lower atmosphere form when water collects on particles, but mesospheric clouds may form directly from ...
Crepuscular rays are noticeable when the contrast between light and dark is most obvious. Crepuscular comes from the Latin word crepusculum , meaning "twilight". [ 2 ] Crepuscular rays usually appear orange because the path through the atmosphere at dawn and dusk passes through up to 40 times as much air as rays from a high Sun at noon .
A nimbostratus cloud is a multilevel, amorphous, nearly uniform, and often dark-grey cloud that usually produces continuous rain, snow, or sleet, but no lightning or thunder. [ 1 ] [ 2 ] [ 3 ] Although it is usually a low-based stratiform cloud, it actually forms most commonly in the middle level of the troposphere and then spreads vertically ...
Clouds of the genus nimbostratus tend to bring constant precipitation and low visibility. This cloud type normally forms above 2 kilometres (6,600 ft) [10] from altostratus cloud but tends to thicken into the lower levels during the occurrence of precipitation. The top of a nimbostratus deck is usually in the middle level of the troposphere.
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 ...
the cloud IR emissivity, with values between 0 and 1, with a global average around 0.7; the effective cloud amount, the cloud amount weighted by the cloud IR emissivity, with a global average of 0.5; the cloud (visible) optical depth varies within a range of 4 and 10. the cloud water path for the liquid and solid (ice) phases of the cloud particles
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Clouds form when the dew point temperature of water is reached in the presence of condensation nuclei in the troposphere. The atmosphere is a dynamic system, and the local conditions of turbulence, uplift, and other parameters give rise to many types of clouds. Various types of cloud occur frequently enough to have been categorized.