Today’s Image of the Day from NASA Earth Observatory features a fascinating display of clouds that appeared over Australia on July 5, 2023. The stunning clouds stretched for more than 600 miles over Western Australia and the Northern Territory.
“Several experts in cloud dynamics who looked at the image found the patterns to be both odd and fascinating, and they could not say with certainty what caused the complex formations based on the image alone,” said NASA. “However, meteorological observations from that time offer clues into what may have been going on.”
Yi Huang, an atmospheric scientist at the University of Melbourne, noted that gravity wave cloud fields are quite common in a stable atmosphere.
“According to temperature profile data, the atmosphere on the morning of July 5 was very stable and well-stratified, with a sharp temperature inversion at the top of the atmospheric boundary layer,” explained NASA. “Disturbances, which can occur when air encounters small ridges and valleys, will produce wave textures in the clouds that look like ripples on a pond.”
Huang suggested the clouds could also be shaped by gravity waves, but on a much larger scale. “Depending on the nature of the perturbation (or perturbations), the gravity waves generated might have different wavelengths.”
Some of the clouds appear to mirror topographical features on the western edge of the formation. Huang said this terrain might have set off a series of waves with longer wavelengths.
Atmospheric scientist Claire Vincent explained that the large-scale features bear some resemblance to fallstreak clouds, which have circular or elliptical boundaries and form when clouds of supercooled water droplets disintegrate from the inside out.
However, Vincent noted that phenomenon typically occurs higher in the atmosphere, whereas the clouds spotted over Australia were warmer, lower-level stratocumulus clouds.
The image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.
Image Credit: NASA Earth Observatory