(Click image to enlarge) Photographed over Lively, Ontario, Canada. © Paul Laplante.
See this photo in the Cloud Gallery here.
Sun pillars are vertical streaks of light that appear above and below a low Sun as it shines through clouds that contain ice crystals, such as the Altocumulus clouds shown here. At night, they are known as moon pillars.
The optical effect is one of the ones that are collectively described as ‘halo phenomena’, and appears on about 25 days of the year over Europe. Sun pillars are caused by the sunlight reflecting off the surface of the ice crystals. So they are rather like an aerial version of the ‘glitter paths’ that appear below the bright sun on the surface of the sea, but it is the faces of tumbling ice crystals that cause the reflections here, rather than then rippled peaks on the ocean. A pillar extending above the Sun like this fine example, looks brightest when the Sun is just below the horizon.
Most of the other the arcs, rings and spots of light that are called halo phenomena only appear when the clouds’ crystals are optically pure, regularly shaped and neatly aligned. But this is not the case for sun pillars. They are like a poor man’s halo phenomenon, for they appear when cloud crystals aren’t so exquisitely refined. Since the sunlight needs only to glance off a surface of the crystals, they can be rough, irregular and jumbled.
Current Cloud of the Month:
March 2010
Previous Clouds of the Month:
February 2010
January 2010
Cloud Reflections (December 09)
Numbers in the Clouds (November 09)
Sun Pillar (October 09)
Convection Clouds (September 09)
‘Pile d’Assiettes’ (August 09)
Cumulus congestus (July 09)
‘Asperatus’ (June 09)
Clouds at Night (May 09)
Sundogs (April 09)
Diamond Dust (March 09)
Cloud Streets (February 09)
Crepuscular Rays (Jan 09)
Valley Fog (December 08)
Cloud Shadows (November 08)
Contrails (October 08)
Mamma (September 08)
Kármán Vortex (August 08)
The Summertime Halo (July 08)
The Nor’west Arch (June 08)
Microbursts (May 08)
Irridescent Clouds (April 08)
Northern Lights – Aurora Borealis (March 08)
Ice halos (February 08)
Lightning (January 08)
Roll Cloud (December 07)
Banner Cloud (November 07)
Stratocumulus (October 07)
The Unclassified Cloud (September 07)
Alexander’s Dark Band (August 07)
Fumulus Snail (July 07)
Distrail (June 07)
Altocumulus undulatus (May 07)
Cumulonimbus capillatus (April 07)
Lacunosus (March 07)
Horseshoe Vortex Cloud (February 07)
Jet-Stream Cirrus (Janurary 07)
Altostratus/Altocumulus/Altowhateveritis (December 06)
Anti-Crepuscular Rays (November 06)
Stratocumulus (October 06)
Altocumulus (September ’06)
The Kelvin-Helmholtz Wave Cloud (August ’06)
The ‘Brocken Spectre’ (July ’06)
‘Whale’s Mouth’ (June ’06)
Noctilucent (May ’06)
Cirrus (April ’06)
Cap Cloud (March ’06)
Fallstreak Holes (February ’06)
Nacreous (January ’06)
Cirrostratus (December ’05)
Tuba (November ’05)
Virga (October ’05)
Cirrocumulus (September ’05)
Altostratus (August ’05)
Cumulus (July ’05)
Mamma (June ’05)
Pileus (May ’05)
Lenticularis (April ’05)
Stratus (March ’05)
Cumulonimbus (February ’05)
Contrails (January ’05)
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