alto-stratus

The weather all day has been more or less overcast with white broken alto-stratus, and for 3 degrees above the horizon there is a grey belt looking like a blizzard of drift, but this in reality is caused by a constant fall of minute snow crystals, very minute.

The Worst Journey in the World Antarctic 1910-1913 Apsley Cherry-Garrard 1922

On the 29th a cold south-easter blew off the ice-cliffs and the sun was trying to pierce a gauzy alto-stratus.

The Home of the Blizzard Being the Story of the Australasian Antarctic Expedition, 1911-1914 Douglas Mawson 1920

The fourth class, called alto-stratus, is a thick sheet of gray or bluish color, sometimes thin enough to let the sun shine through.

The Boy with the U. S. Weather Men Francis Rolt-Wheeler 1918