Morning Glory Cloud

From fine wisps of cirrus to drooping, soggy sheets of nimbostratus, from anvil-topped thunderstorms to fog and mist, most kinds of clouds can found in many different places across the world. Thunderstorms are largely the same in Siberia as they are in Seattle; cirrus clouds caress the sky over Finland just as they do above herds of elephants in central Africa. Not so the Morning Glory Cloud -- a kind of cloud occurs predictably only at one place on Earth -- the Gulf of Carpenteria in Australia's northern region, facing Indonesia. A Morning Glory cloud may develop elsewhere, but it is very rare and completely random save at this one locale.

Morning Glory clouds are spectacular, strange, and beautiful. Each one is a completely distinct, nearly smooth roll of cloud which is only around a mile in diameter but can be hundreds of miles long. These clouds may form in large numbers, lying parellel to each other like white molehills crossing the sky. They travel quickly and often have powerful wind gusts associated with them. The causes of these clouds are very complex, but there is no doubt that they are extremely distinctive, beautiful, and interesting weather phenomena, whose rarity makes them even more intriguing.

Why Morning Glory clouds form

Morning Glory clouds form over the Gulf of Carpenteria much more often than anywhere else in the world because of a unique combination of geographical features, including the shape of the land and the presence of several different seas nearby.

The Cape York peninsula on the east side of the Gulf is the source for the area's predictable Morning Glory clouds. During the day, the peninsula grows hot, and this creates an updraft that pulls sea air in from the Gulf on one side and the Coral Sea on the other, building a vast ridge of cold air over Cape York. Then, overnight, a temperature inversion occurs over the Gulf, which means that the air is cold at the surface and warm above. The ridge of cold air over the Cape York peninsula literally collapse under its own weight once the sun's heat no longer provides it with the lifting updraft, and the cold air slides down under the Gulf's inversion in waves, literally making the air undulate like an ocean. The wave 'crest' is lifted high enough for the moisture to condense into cloud, forming a Morning Glory cloud.

Extreme humidity is also needed for the cloud's formation -- so the local people can generally predict when Morning Glory clouds will form a few hours beforehand by noting how humid conditions are at ground level. If the humidity is not present, the same effect presumably happens aloft, but there isn't enough moisture in the air 'wave crests' to condense into clouds and the sky is bare in the morning.

The creation of Morning Glory clouds at the Gulf of Carpenteria requires such a specialized set of circumstances to happen that it is something of a mystery how they can form anywhere else on Earth, but at odd intervals, one or several of these clouds will appear on a coastline somewhere else. Brazil, England, the United States, and Russia have all witnessed a fluke Morning Glory cloud, whose presence is currently inexplicable.

The effects of Morning Glory clouds

Morning Glory clouds seem to have little effect on overall weather, but they have a powerful hold on the human imagination. Many people come to the Gulf of Carpenteria to witness the clouds, and some come to use their gliders and light aircraft to 'ride' on the winds accompanying the clouds -- a dangerous but spectacularly beautiful experience, with the Morning Glory cloud seeming to extend to infinite in its swift white purity.