Timothy Birdnow

I really don't know clouds....at all.

Abstract

We briefly review the dominant role of clouds in Earth’s climate. The earliest observational

studies of heat transfer through Earth’s atmosphere, for example, those of John Leslie around

1800, showed that clouds have a large effect on radiative heat transfer from Earth’s surface to

space. Greenhouse gases also affect heat transfer, but much less than clouds. For example, "in

stantaneously doubling” CO2 concentrations, a 100% increase, only decreases radiation to space

by about 1%. To increase solar heating of the Earth by a few percent, low cloud cover only needs

to decrease by a few percent. The first half of this paper reviews observational facts about how

clouds affect heat transfer. The second half gives a brief summary of the new 2n-stream radiation

transfer theory for quantitatively analysing how clouds scatter radiation incident from outside the

cloud, and how they emit thermal radiation generated by their particulates.

Keywords: Pyranometer, Pyrgeometer, Radiative Transfer, Clouds

Submitted 2024-12-28, Accepted 2025-01-02. https://doi.org/10.53234/scc202501/02

Ruixue Li, Jiming Li, Bida Jian, Lijie Zhang, and Jiayi Li

Abstract

Persistent global warming is modulated by cloud changes, yet the specific contributions and associated controlling factors remain inadequately quantified. Using CERES radiation data with a surface energy-balance framework, we quantify the contribution of cloud radiative changes to decadal surface temperature trends over 2002–2023. Cloud changes exert a weak net effect on global mean warming due to near-cancellation between shortwave warming and longwave cooling, but strongly modulate the meridional pattern of zonal-mean warming. Specifically, clouds enhance warming in low- and mid-latitudes while mitigating warming at high latitudes. This pattern is associated with a systematic redistribution of cloud occurrence from low-/mid-level cloud types to high-level optically thin clouds, which reduce planetary albedo and weaken cloud longwave emission. These changes exhibit hemispheric difference. In 30–60° N, the region contributing most to global warming, the decline in the cloud-reflected solar radiation is mainly driven by decreased cloud fraction, linked to elevated sea surface temperatures, aerosol reductions, and mid-tropospheric drying. In 30–60° S, reduced cloud reflectivity resulting from decreased cloud optical thickness and increased liquid droplet radius dominates. However, at high latitudes in both hemispheres, increased mid-/high-clouds and enhanced cloud reflectivity, driven by enhanced moisture, upper-tropospheric static stability and increased cloud optical thickness, lead to greater reflected solar radiation and reduced downwelling longwave radiation, thereby attenuating local warming. Our results establish a direct observational link between cloud-type changes, planetary albedo decline, and contrasting warming across latitude zones, characterizing the cloud-radiative changes in recent climate change.

end

The Earth has been seeing a reduction in cloud cover/planetary albedo for decades now. Gee; maybe Mr. Sun is what is warming the Earth after all and not our industrial emissions.

Posted by: Mike at September 17, 2026 04:59 PM (9Epdh)

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