When working for the British Antarctic Survey I saw many incredible things and this indeed was one of them, the following pictures were taken by the serving Chief Officer and very good friend of mine Euan as my camera had run out of juice and to be fair wasn’t as good as Euan’s camera. They were taken in the early hours over the vast mountain range of South Georgia.
Lenticular clouds (Altocumulus lenticularis) are stunning stationary lens-shaped clouds that form at high altitudes, normally in perpendicular alignment to the wind direction. This type of cloud is a common sight around the Island of South Georgia and I’m sure you will agree they are quite spectacular. Due to their shape, they have even been offered as an explanation for some Unidentified Flying Object (UFO) sightings.
I certainly wont blame you if you came just to see the beautiful pictures, but the following is a little technical jargon for those interested in how these unique formations are made:
Where stable moist air flows over a mountain or a range of mountains, a series of large-scale standing waves may form on the downwind side. If the temperature at the crest of the wave drops to the dew point, moisture in the air may condense to form lenticular clouds. As the moist air moves back down into the trough of the wave, the cloud may evaporate back into vapor. Under certain conditions, long strings of lenticular clouds can form near the crest of each successive wave, creating a formation known as a “wave cloud.” The wave systems cause large vertical air movements and so enough water vapor may condense to produce precipitation. The clouds have been mistaken for UFOs (or “visual cover” for UFOs) because these clouds have a characteristic lens appearance and smooth saucer-like shape. Bright colors (called irisation) are sometimes seen along the edge of lenticular clouds.
Pilots of powered aircraft tend to avoid flying near lenticular clouds because of the turbulence of the rotor systems that accompany them, but glider pilots actively seek them out. The precise location of the rising air mass is fairly easy to predict from the orientation of the clouds. “Wave lift” of this kind is often very smooth and strong, and enables gliders to soar to remarkable altitudes and great distances. The current gliding world records for both distance (over 3,000 km; 1,864 mi) and altitude (15,460 m; 50,721 ft) were set using such lift.
For mariners, they are just something new to brighten our days.
|Euan is a dab hand with a canon!!!|