Newest observations

Contact information

Skywarden,
Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki
taivaanvahti(at)ursa.fi

Ursa Astronomical Association

Other special clouds - 18.10.2016 at 18.06 Lahti Observation number 57961

Visibility IV / V


An impressive looking hole cloud seen in Lahti Market Square


Additional information
  • Havainto
    • Other special clouds
  • Cloud coverage in the sky
    • Very small area
  • Other special clouds
    • Fallstreak hole info

      Fallstreak hole (Hole punch cloud) is a rare phenomenon observed in cloud cover.

      Altocumulus clouds consist mainly of subcooled cloud droplets, which can be well below freezing, but which have not yet frozen in the absence of suitable freezing cores.

      When freezing nuclei, such as small ice crystals, come into contact with the cloud, the droplets of clouds may begin to freeze outward from this point so that an annular opening appears to form in the cloud. Such an opening is called a hole cloud.

      One source of freezing cores may be airplanes that create a cloud of holes as they pass through the altocumulus layer. Hole clouds can also be oblong in shape when the aircraft has flown a little longer at cloud height. In this case, ice crystals floating down from the opening remains in its path. In the middle of these openings or canals, a thin line of ice crystals, or Virga, visible below the cloud layer, can typically be seen. If the sun happens to be at a suitable distance from this rain line, a halo phenomenon, such as a side sun, can be detected in the wake.

      A hole cloud formed in the Altocumulus layer with a rain line of ice crystals, or Virga, in the middle. Image by Jari Luomanen.

Comments: 4 pcs
Eero Karvinen - 18.10.2016 at 22.51 Report this

Nätisti erottuu tuo oranssi sadejuova! Katselin ja kuvasin samaa ilmiötä.

Olli Sälevä - 19.10.2016 at 10.14 Report this

Varsin "dramaattinen" ilmestys.

Tarja Hämäläinen - 23.10.2016 at 21.02 Report this

Upean näköinen tuo pilvi.  En ole ennen tiennyt, että on sadejuova  kauniin oranssi on

Heidi Rikala - 23.10.2016 at 21.40 Report this

Upea kuva reikäpilvestä. Mahtavat värit. Olisipa kiva nähdä tuollainen.

Send a comment

Comments are checked and moderated before publication If you want to contact the observer directly about possibilities to use these images, use the Media -form.

*

*

*
characters left

By sending in this comment I confirm, that I've read and understood the the observation system's privacy policy.