photo #6818881

A sun pillar is a tall shaft of light that appears above or below the Sun when it’s low in the sky. Sharon Lombard spotted this upper sun pillar near Los Osos, California, US when the Sun was over the horizon. The phenomenon was caused by sunlight reflecting off the undersides of plate-shaped ice crystals in the clouds. Usually, the ice crystals forming sun pillars are found in high clouds like Cirrus or Cirrostratus or in ground-level ice fog, known as diamond dust, but these look to have been in the mid-level cloud Altocumulus. Low temperatures up at cloud level likely caused some of its water droplets to freeze into the plate-shaped crystals. These will likely have been falling through the sky, wobbling as they descended like autumn leaves, the countless fleeting glints reflecting towards Sharon from their undersides all combining as a steady pillar of light – a vertically extended memory of a sunset just past.