From The Washington Post via The Denver Post:
In a new study published in Nature on Monday, scientists say they have for the first time thoroughly documented one of the most profound planetary changes yet to be caused by a warming climate: The distribution of clouds all across the Earth has shifted, they say.
And moreover, it has shifted in such a way – by expanding subtropical dry zones, located between around 20 and 30 degrees latitude in both hemispheres, and by raising cloud tops – as to make global warming worse…
That these things would happen in theory, based on our understanding of the physics of the atmosphere, has long been expected. The physical reasons for the expectation get complicated fast, involving factors such as the atmospheric “Rossby radius of deformation,” and how the Earth’s rotation bends the path of winds – the so-called Coriolis force, Norris explains. But all of this has long been an expectation based on runs of sophisticated climate simulations that embed within their coding the fundamental equations that govern the behavior of the atmosphere.
However, the study painstakingly pieced together images from weather satellites between the years 1983 and 2009 – correcting for the numerous known quirks of these satellites that have also made their measurements of atmospheric temperatures a messy affair – to line up pre-existing theory with observations.
“We’re seeing what the climate models think the pattern of cloud change would be,” Norris said.
Here’s how the paper summarizes the changes, region by region: “cloud amount and albedo [i.e., reflectivity] increased over the northwest Indian Ocean, the northwest and southwest tropical Pacific Ocean, and north of the Equator in the Pacific and Atlantic oceans. Cloud amount and albedo decreased over mid-latitude oceans in both hemispheres (especially over the North Atlantic), over the southeast Indian Ocean, and in a northwest-to-southeast line stretching across the central tropical South Pacific.”