Arctic Ice-Blue Clouds at Dawn


We were treated to a good display of noctilucent clouds last night. Or should I say early this morning! At this time of year, many a night is spent keeping a watchful vigil for noctilucent clouds. They often appear at their best before dawn.

That was the case July 5/6. The night started with a decent display of these northern sky clouds in the northwest after sunset and just before midnight. But then as the Sun dropped lower below the horizon, the lighting angles changed and the clouds disappeared. A low aurora display took their place through most of the night.

Then, at 3 am or so, as the lighting from the rising Sun hit the right angle coming over the Pole, the Arctic ice clouds reappeared, now in the northeast. Sequences of shots showed a rapid east to west motion of the clouds, driven by winds at the edge of space, at the clouds’ extreme altitude of 80 km or so.

This shot is with a 16-35mm zoom, set to 24mm and takes in the bright star Capella at upper right, a useful “survey marker” for measuring angles and cloud altitudes. I took this at about 3:30 am. MDT.

— Alan, July 6, 2011 / Image © 2011 Alan Dyer