Clouds are climate wildcards says Phys.org. This study focuses on tropical convective clouds. It seems that ‘the product of the number of clouds and their perimeter remains constant, a mathematical law known as scale invariance.’
Quoting from the ‘plain language summary’ of the study:
‘Narrowing uncertainty in forecasts of climate change has been hindered by the difficulty of representing the extraordinary complexity of clouds. Here, we show how the numbers and sizes of clouds, and their total amount, can be derived thermodynamically knowing just the atmospheric temperature and humidity profile.’
As usual an assumption of future warming is built-in, but we have to live with that approach even if we question it.
Take a look at the clouds, if there are any in your sky right now. Watch the billows, the white lofty tufts set against the blue sky. Or, depending on your weather, watch the soft grey edges smear together into blended tones that drag down through the air to the ground.
They’re an inspiration to most of us, but a nightmare for climate scientists. Clouds are exceptionally complex creatures, and that complexity makes it difficult to predict how and where they’ll form—which is unfortunate, since those predictions are essential to understanding precipitation patterns and how our climate will change in the future.
But University of Utah researchers may have found a way to greatly reduce the difficulty of predicting formation of clouds. The results, published today in Journal of Geophysical Research-Atmospheres could fill a key gap in scientists’ understanding of how climate change may play out.
“We used simple thermodynamics,” says atmospheric sciences professor Tim Garrett, “to predict that there should be many small clouds and few large clouds in proportions that obey simple mathematical laws.”
Clouds are climate wild cards
Clouds, particularly those in the tropics, are part of the Earth’s system for getting rid of excess heat generated by the sun. That’s why they matter to climate scientists. They’re part of a vertical conveyor belt, lifting hot buoyant air up to an altitude where the heat can be easily radiated into the cold blackness of space. But clouds can play with heat in other ways.
“Think of how quickly a cloud can change the temperature during a summer picnic,” says postdoctoral scholar and study co-author Ian Glenn. “A slight change in the fraction or distribution of even a few small clouds on an otherwise nice clear day can make or break an outing.”
Clouds constantly grow and shrink as they exchange air with surrounding dry air. So far, it’s unclear how clouds factor into the effects of global climate change—will clouds slow down warming? Or enhance it? Will warming create more clouds? If so, what regions will be most affected?
. . .
Clouds are leaky conduits
Let’s go back to the concept of clouds as conduits of heat into the upper atmosphere. A tall, sharp, white cloud is composed of droplets of water, in contrast to the clear, blue, relatively drier air around it. The white, wet clouds and the blue, dry air are in constant contact with each other, sharing a common boundary. It’s this boundary that got Garrett thinking.
As water droplets form inside clouds, a little bit of heat is released, making the clouds buoyant in the atmosphere. Garrett says that this makes clouds efficient at their job of lifting heat away from the ground—and also means that the hot, rising air is turbulent and can spill out of the sides of the cloud as it rises.
“This realization about clouds as leaky conduits made me think that the place to look for understanding clouds and climate was not their areas looking down, as has commonly been the focus, but instead their edges,” Garrett says.
Full report here.
via Tallbloke’s Talkshop
July 24, 2018 at 03:15AM
Iowa Climate Science Education 