Beautiful chevron-shaped cloud patterns have been pictured stretching over the southern Indian Ocean by an astronaut aboard the International Space Station.
The photograph, featured as NASA Earth Observatory's April 16 Image of the Day, shows the strange cloud patterns splaying out like a wake around the Crozet Islands, situated roughly 1,500 miles east of South Africa and around the same distance north of Antarctica. The picture was taken on January 8, earlier this year.
These bizarre clouds are known as wave clouds, or gravity waves, according to the National Oceanic and Atmospheric Administration (NOAA).
Astronaut photograph ISS068-E-39246 was acquired on January 8, 2023, with a Nikon D5 digital camera using a focal length of 50 millimeters. It shows the wave clouds around the Crozet Islands in the south Indian...Astronaut photograph ISS068-E-39246 was acquired on January 8, 2023, with a Nikon D5 digital camera using a focal length of 50 millimeters. It shows the wave clouds around the Crozet Islands in the south Indian Ocean The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed.Provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 68 crew.Wave clouds are a result of atmospheric internal waves, which are fluctuations in the air formed when air moves over areas of higher ground, being forced upwards, before being pulled down again by gravity. This then results in ripples of air, rising up and down like disturbed water in a tub.
The characteristic clouds form on the cooler crests of these ripples, with the water condensing due to the lower temperatures, but evaporate again at the troughs of the ripples due to the air heating up again via adiabatic heating. This then leads to the stripy pattern of clouds as snapped from space, also known as cloud streets, stretching out like the wake of a boat in a still lake.
This process is what likely occurred as air flowed over the Crozet Islands archipelago, and appears to be a fairly common occurrence in this area. A similar phenomenon was spotted over this same set of islands in 2014 by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite, and above one of the Crozet Islands, Île aux Cochons, in 2012, also by one of the ISS astronauts.
This island in particular has a summit of around 2,543 feet, NASA Earth Observatory reported at the time, and the frequency of wave cloud formation over these islands is due to stable air masses over the southern Indian Ocean flowing over the islands' mountains.
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The Crozet Islands are uninhabited apart from numerous seals, penguins, and sea birds, as well as a few research stations. Not exactly a sunny island getaway, the Crozet Islands receive over 300 days of rain each year, and experience an average temperature of 37 degrees Fahrenheit in the winter months, and 46 degrees Fahrenheit in the summer.
Home to the world's largest colony of king penguins, the Île de la Possession is where the Alfred-Faure research station is based. Scientists study the 700,000-strong breeding pairs present on the island, which amounts to around half the world's population of king penguins.
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