All About the Beautiful Morning Glory Clouds of Australia
A Morning Glory cloud is a roll cloud that can be 1000 kilometres
long and 1 to 2 kilometres high. These clouds can move up to a speed of
60 kilometres per hour. It is a very uncommon phenomenon and is often
accompanied by sudden wind squalls, an increase in the vertical
displacement of air parcels and a jump in pressure at the surface. There is a strong vertical motion in front of the cloud that brings in
air up through the cloud that creates the rolling appearance. It is also
described as a wave with a single crest and moves on without any change
in shape or speed. The Morning Glory clouds mainly occur in Gulf of
Carpentaria, northern Australia.
Causes behind the formation
Though it is very difficult to understand the clouds because of its
complex nature, some researches suggest that the main cause is the
Mesoscale circulations that are associated with sea breezes developing
over the peninsula and the gulf. But according to some locals in
Australia, such clouds occur when there is high humidity in the area
which provides moisture for the clouds to form.
Formation of the clouds
Cape York is a peninsula that falls to the east of the gulf. The breeze
from the Coral Sea coast blows in from the east and the breeze from the
gulf blows in from the west and meets in the middle of the peninsula.
This forces the air to rise and form a line of clouds over the spine of
the peninsula. With night, the air descends when it cools up and a
surface inversion takes over the gulf. The densities are different above
and below the inversion. The air descending from the peninsula in the
east goes under the inversion layer and creates a wave across the gulf.
The air rises in front of the wave and sinks at the back.
In the morning, the air is saturated enough and the rising air in the
front produces a cloud that forms the edge of the wave and evaporates at
the back.
Places of occurrence
To see Morning Glory in Australia, Burketown in the remote Far North
Queensland is the best place to go for. Such cloud formation also takes
place occasionally off the Mexican coast in the Sea of Cortez, Sable
Island. Another incident of such formation had taken place at Yarmouth,
Nova Scotia. But unlike the morning clouds of the Gulf of Carpentaria,
clouds in Nova Scotia appear in the evening.
Time of occurrence
The Morning Glory clouds generally occur around September and October in
Australia’s North Queensland. At this time, this place also sees an
influx of a great number of glider and hang-glider pilots.
|
