#cloud cover

How it started and, how it finished…

Yesterday (13.11), we decided that an afternoon walk up to Meadow Wood would be a good idea. That's because in the morning, it was bright and sunny. When we set off in the afternoon, the cloud was starting to bubble up but, there was still a fair bit of blue sky. That started to change during the course of the walk as the cloud built up and the light conditions deteriorated. Needless to say, the mood and atmosphere changed with the build of the cloud and the fading light. I think the two images shown above, taken at the start and the end of the walk, pretty much sum up that transformation. Such are the joys of late autumn photography in England…

Annual mean maps of Moderate Resolution Imaging Spectroradiometer Total Cloud Cover (top) and the Clouds and the Earth's Radiant Energy System Shortwave Cloud Radiative Effect (bottom) for the 2001–2024 period. Credit: Geophysical Research Letters (2025). DOI: 10.1029/2025GL114882

Excerpt from this EcoWatch story:

Earth’s cloud cover has been shrinking rapidly, contributing to the world’s rising temperatures, according to a new NASA-led analysis of satellite observations.

The researchers found that during each decade of the past 24 years, 1.5 to three percent of the planet’s “storm cloud zones” in the middle latitudes and tropics have been contracting.

“This cloud contraction, along with cloud cover decreases at low latitudes, allows more solar radiation to reach the Earth’s surface. When the contribution of all cloud changes is calculated, the storm cloud contraction is found to be the main contributor to the observed increase of the Earth’s solar absorption during the 21st century,” the authors of the study wrote.

The trend has been associated with changing wind patterns, storm systems shifting poleward and the widening of the tropics — all well-established planetary responses to climate change, a press release from Monash University said.

Fewer clouds mean less sunlight is being reflected back into space, amplifying the warming effect of human-produced greenhouse gas emissions and driving up temperatures worldwide.

Climate scientist Christian Jakob, co-author of the study and a professor of climate modeling at Monash’s School of Earth, Atmosphere and Environment, said reduced cloud cover is now considered the biggest contributor to the increase in the planet’s absorption of solar radiation.

“We’ve long known that changes in atmospheric circulation are affecting clouds,” Jakob said in the press release. “For the first time, we now have research showing those shifts are already driving major changes in how much energy the Earth absorbs. It’s an important piece in the puzzle of understanding the extraordinary recent warming we observed, and a wake-up call for urgent climate action.”

Being able to predict where clouds form more accurately, as well as how much solar radiation they reflect, will be crucial to anticipating the scale and speed of future warming.