Morning glory cloud
Encyclopedia
Northern Australia
The term northern Australia is generally known to include two State and Territories, being Queensland and the Northern Territory . The part of Western Australia north of latitude 26° south—a definition widely used in law and State government policy—is also usually included...
's Gulf of Carpentaria
Gulf of Carpentaria
The Gulf of Carpentaria is a large, shallow sea enclosed on three sides by northern Australia and bounded on the north by the Arafura Sea...
is the only known location where it can be predicted and observed on a more or less regular basis. The settlement of Burketown attracts glider pilots
Gliding
Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word soaring is also used for the sport.Gliding as a sport began in the 1920s...
intent on riding this phenomenon. (see Burketown, Queensland#Climate)
Description
Morning Glory clouds can most often be observed in Burketown in September to mid-November, when the chance to see it early in the morning is approximately 40%.A Morning Glory cloud is a roll cloud that can be up to 1000 kilometres (621.4 mi) long, 1 to 2 km (0.621372736649807 to 1.2 ) high, often only 100 to 200 m (328.1 to 656.2 ) above the ground and can move at speeds up to 60 kilometres (37.3 mi) per hour. Sometimes there is only one cloud, sometimes there are up to eight consecutive roll clouds.
The Morning Glory is often accompanied by sudden wind squalls, intense low-level wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
, a rapid increase in the vertical displacement of air parcels, and a sharp pressure jump at the surface. In the front of the cloud, there is strong vertical motion that transports air up through the cloud and creates the rolling appearance, while the air in the middle and rear of the cloud becomes turbulent and sinks.
The cloud can also be described as a solitary wave
Solitary wave
In mathematics and physics, a solitary wave can refer to* The solitary wave or wave of translation, as observed by John Scott Russell in the Union Canal, near Edinburgh in 1834...
or a soliton
Soliton
In mathematics and physics, a soliton is a self-reinforcing solitary wave that maintains its shape while it travels at constant speed. Solitons are caused by a cancellation of nonlinear and dispersive effects in the medium...
, which is a wave that has a single crest and moves without changing speed or shape.
History of exploration
Unusual cloud formations have been noticed here since ancient times. The local Garrawa Aboriginal peopleAustralian Aborigines
Australian Aborigines , also called Aboriginal Australians, from the latin ab originem , are people who are indigenous to most of the Australian continentthat is, to mainland Australia and the island of Tasmania...
called it kangólgi. Royal Australian Air Force
Royal Australian Air Force
The Royal Australian Air Force is the air force branch of the Australian Defence Force. The RAAF was formed in March 1921. It continues the traditions of the Australian Flying Corps , which was formed on 22 October 1912. The RAAF has taken part in many of the 20th century's major conflicts...
pilots first reported this phenomenon in 1942.
The Morning Glory cloud of the Gulf of Carpentaria has been studied by multiple teams of scientists since the early 1970s. The first studies were published by Reg H.Clarke (University of Melbourne
University of Melbourne
The University of Melbourne is a public university located in Melbourne, Victoria. Founded in 1853, it is the second oldest university in Australia and the oldest in Victoria...
). Multiple studies have followed since then, proposing diverse mathematical models explaining the complex movements of air masses in region.
Causes
Despite being studied extensively, the Morning Glory cloud is not clearly understood.Regardless of the complexity behind the nature of this atmospheric phenomenon, some conclusions have been made about its causes. Through research, one of the main causes of most Morning Glory occurrences is the mesoscale
Mesoscale meteorology
Mesoscale meteorology is the study of weather systems smaller than synoptic scale systems but larger than microscale and storm-scale cumulus systems. Horizontal dimensions generally range from around 5 kilometers to several hundred kilometers...
circulations associated with sea breezes that develop over the peninsula and the gulf. On the large scale, Morning Glories are usually associated with frontal systems crossing central Australia and high pressure in northern Australia. Locals have noted that the Morning Glory is likely to occur when the humidity in the area is high, which provides moisture for the cloud to form, and when strong sea breezes have blown the preceding day.
Scenario for formation
The following is a summary of the conditions that cause the Morning Glory cloud to form in the Gulf of Carpentaria (after hypothesis of R.H.Clarke, as described in 1981). First, Cape YorkCape York Peninsula
Cape York Peninsula is a large remote peninsula located in Far North Queensland at the tip of the state of Queensland, Australia, the largest unspoilt wilderness in northern Australia and one of the last remaining wilderness areas on Earth...
which is the peninsula that lies to the east of the gulf is large enough that sea breezes develop on both sides. The breeze from the Coral Sea coast blows in from the east and the breeze from the gulf blows in from the west. The two breezes meet in the middle of the peninsula, forcing the air to rise there and form a line of clouds over the spine of the peninsula. When night comes, the air cools and descends and at the same time a surface inversion forms over the gulf (where air temperature increases with height). The densities in this stable layer are different above and below the inversion. The air descending from the peninsula to the east goes underneath the inversion layer and this generates a series of waves or rolling cylinders which travel across the gulf. These cylinders of air roll along the underside of the inversion layer, so that the air rises at the front of the wave and sinks at the rear. In the early morning, the air is saturated enough so that the rising air in the front produces a cloud, which forms the leading edge of the cylinder, and evaporates in the back, hence forming the Morning Glory cloud. The cloud lasts until the surface inversion disappears with the heating of the day.
This is one scenario that explains the formation of the Morning Glory Cloud over the Gulf of Carpentaria, but other explanations have also been proposed.
There are other ways in which Morning Glory clouds form, especially in rarer cases in other parts of the world, but these are far less understood.
Local weather lore in the area suggests that when the fridges
Refrigerator
A refrigerator is a common household appliance that consists of a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room...
frost over and the café tables' corners curl upwards at the Burketown Pub, there is enough moisture in the air for the clouds to form. Reportedly, all winds cease at ground level as the cloud passes over.
One vantage point to see Australia's Morning Glory is from Burketown in the remote Far North Queensland
Far North Queensland
Far North Queensland, or FNQ, is the northernmost part of the Australian state of Queensland. The region, which contains a large section of the Tropical North Queensland area, stretches from the city of Cairns north to the Torres Strait...
around September and October. Towns in this part of the world are small and far apart, and Burketown has an influx of glider and hang-glider pilots at this time of year.
Other reported occurrences
Although the Morning Glory clouds over the southern part of Carpentaria Gulf are the most frequent and predictable, similar phenomena have occasionally been observed elsewhere, e.g., over central United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...
, Berlin, Germany, Eastern Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
, and other maritime regions of Australia.
Morning Glory clouds have occasionally been reported in the Sea of Cortez off the Mexican
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
coast. The phenomenon has also been observed from Sable Island
Sable Island
Sable Island is a small Canadian island situated 300 km southeast of mainland Nova Scotia in the Atlantic Ocean. The island is a year-round home to approximately five people...
, 180 km southeast of Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
. A Morning Glory also passed through Yarmouth, Nova Scotia
Yarmouth, Nova Scotia
Yarmouth is a town and fishing port located on the Gulf of Maine in rural southwestern Nova Scotia, Canada. It is the shire town of Yarmouth County. The town is located in the heart of the world's largest lobster fishing grounds and has Canada's highest lobster catch.- History :The townsite may...
in April 2009. In contrast to the Gulf of Carpentaria where the Morning Glory is visible in the morning, those in Nova Scotia have all occurred during the evening. Rare examples have been observed via satellite observation over the Joseph Bonaparte Gulf
Joseph Bonaparte Gulf
Joseph Bonaparte Gulf is a large body of water off the coast of the Northern Territory, Australia and Western Australia. It was named after Joseph Bonaparte, brother of Napoleon and King of Naples and then Spain by French explorer and naturalist Nicholas Baudin in 1803...
in the Eastern Kimberley region of Australia as well as over the Arabian Sea
Arabian Sea
The Arabian Sea is a region of the Indian Ocean bounded on the east by India, on the north by Pakistan and Iran, on the west by the Arabian Peninsula, on the south, approximately, by a line between Cape Guardafui in northeastern Somalia and Kanyakumari in India...
. A Morning Glory cloud was observed in 2007 over the Campos dos Goytacazes
Campos dos Goytacazes
Campos dos Goytacazes is a municipality and city located in the northern area of Rio de Janeiro State, Brazil, with a population of 463,545 inhabitants. Its area is 4,031.910 km², which makes it the largest municipality in the state and its elevation is 14 m...
bay in the state of Rio de Janeiro, Brazil. In August 2011, it happened again over Peregrino
Peregrino
Peregrino is an oil field located offshore Brazil east of Rio de Janeiro in the southwest part of the Campos Basin area, with about of oil in place within the sanctioned area - discovered in 2004. The field was formerly known as Chinook....
Field in South Campos Basin
Campos Basin
Campos Basin is a petroleum rich area located offshore of Rio de Janeiro, Brazil. It has a total area of 100,000 square kilometres, with 40 fields discovered and operated by Petrobras....
in Brazil. The phenomenon was also recorded on Batroun's shore (Lebanon — Middle East) in September 2004.
External links
- Menhofer A, Smith RK, Reeder MJ, Christie DR (1997) “Morning-Glory” Disturbances and the Environment in which They Propagate. Journal of the Atmospheric Sciences: Vol. 54, No. 13 pp. 1712–1725
- Smith, Deborah. (2002) Morning Glory lures scientists to ride cloud nine The Sydney Morning Herald: September 16, 2002 -see - http://www.austms.org.au/Jobs/Library1.html
- http://www.meteo.physik.uni-muenchen.de/~roger/Tropics/Tropclds-o.htm regarding Tropical cloud lines
- morninggloryaustralia.com Meteorological information, photos and video of the Morning Glory Cloud.
- DropBears.com on the Morning Glory phenomenon, with aerial photos of the cloud.
- hang glider soaring hang gliding on the Morning Glory phenomenon, with aerial photos and videos of the cloud.
- ABC Australia with images of soaring the Morning Glory.
- Cloud Appreciation Society Article on the Morning Glory, images, and video.
- Sable Island Green Horse Society Sable Island Soliton in the afternoon of 13 June 2003 - The same formation as a classic Gulf Morning Glory Cloud
- Sable Island Green Horse Society More photos of the Sable Island Soliton
- Wired.com Wired Science blog post about the clouds.