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Other special clouds - 2.8.2017 at 16.15 Uusikaupunki Observation number 65752

Visibility IV / V

Janne Kari, Porin Karhunvartijat

A quickly passed Pileus stack on top of a thundercloud. Shooting direction to the northeast. First picture 400mm, second picture 100mm. It took a few minutes from the observation so the pile had rested. However, for the identities of the lenticularis stack, Pileus was not.

Additional information
  • Havainto
    • Other special clouds
  • Cloud coverage in the sky
    • Very small area
  • 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.

Technical information

Canon EOS6D, Canon EF100-400 L II, Photoshop CC2017

Comments: 1 pcs
Lauri Kangas - 2.8.2017 at 20.42 Report this

Kyllä tuo sinänsä on pileus, samaten lenticularis, vaikkakin vähän lyhytikäinen.

Syntymekanismi on näillä sama, eli pileuksessa nouseva kumpupilvi painaa yllään olevia vähän stabiilimpia ilmakerroksia mutkalle ja nousemaan pakotettu ilma jäähtyy adiabaattisesti. Jos näiden kerrosten kosteus oli juuri sopiva, jäähtyminen saa aikaan kosteuden tiivistymisen ja syntyy linssipilvi. Nousun jatkuessa cumulus puhkaisee kerrokset kokonaan ja Pileus sulautuu osaksi kohoavaa pilvitornia.

Lenticularis syntyy ihan samalla tavalla johtuen milloin mistäkin. Joskus stabiili inversiokerros menee mutkalle vuoren tai vuoriston yli puhaltavan tuulen takia, joskus taas inversion alla voi olla konvektiota joka ei jaksa nousta kerroksen läpi. Sopivan suuntaisilla tuulilla voi ilman vuoriakin syntyä edes jonkin aikaa pysyvä tilanne.

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