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Ursa Astronomical Association

Other special clouds - 24.7.2021 at 11.42 Vantaa Observation number 99890

Visibility IV / V


Heading northwest-north in the form of stretch-shaped lens cloud stacks, with thicker spheres here and there. Plenty of ordinary lentil clouds: half of the west-north sky on the south-northeast axis, on the sky and south-west. In the northeastern sky, formations similar to KH wave clouds disintegrated after the second wave-like formation.

I missed the beginning, probably 1-2 h. After 1 p.m., some lens-cloud-like formations were still visible in the northwest.


Additional information
  • Havainto
    • Other special clouds
  • Cloud coverage in the sky
    • Covered 3/8 of the sky
  • Other special clouds
    • Stacked lenticularis info

      Stacked lenticularis clouds, is a phenomenon in which there are several lentil-like clouds piled on top of each other. In the sky watch, the practical boundary between the conventional altocumulus lenticularis and the rarer lenticularis stack is considered to be at least three overlapping lenticular, i.e. layer-like, clouds.

      Lenticularis clouds are streamlined, flat cloud shapes. Typically, they occur when a mountain or mountain causes a vertical disturbance to the air flow. At the top of the resulting air wave, moisture may condense into cloud droplets, allowing a smooth lenticular layer to be observed. Sometimes such clouds also form without strong terrain in connection with various weather phenomena.

      Lenticularis clouds themselves are not uncommon and they can be seen quite often. Overlapping lentil cloud layers are clearly a less frequently seen phenomenon. Such a layerish pile cloud is formed when the wetter and drier layers of air alternate in the air. At that time, moisture condenses in some layers and not in others, so that even a very large number of lenticular layers can be detected.

      Only such clearly formed, layered lenticular clouds are collected in the sky due to their rarity.

      In Iceland, a layered lenticular cloud formed in a wave caused by mountains. Image from Wikipedia.

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