Climate Discussion Group 2024, CDG2024
Discussion - Climate C5
October - December 2024 + select continuing discussions in 2025
C5 Albedo, reflection of inbound solar rays, scattering and absorption of radiation.
Jan. 2, 2025
W.A. Wijngaarden
W. Happer Canada, USA
Radiation Transport in Clouds
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, “instantaneously 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.
Dec. 31, 2024
Gerald Ratzer
Canada
CDG2024 Final Technical Report
Climate Discussion Group
Climate change is one of the most debated topics of our time, covering everything from the impact of weather patterns to economic stability and human health. As scientific opinions evolve around the causes and consequences of a warming planet, the urgency for effective policy responses becomes paramount. For policymakers, this means not only understanding the complex interplay of environmental, social, and economic factors but also crafting effective strategies. This is a discussion from invited participants about an understanding of Climate on the technical level.
Dec. 22, 2024
Gerald Ratzer
Canada
C5 Albedo, scattering and absorption of radiation.
Gerald Ratzer (22Dec) starts with an AI response to the title, which is then analyzed. There is a further analysis of the Energy Balance diagram that appears in the IPCC AR5. Ned Nikolov has an extended discussion on this in his long video, starting at minute 19, where the IPCC errors are explained.
Solar Radiation - albedo, scattering, absorption
Solar radiation undergoes several processes as it travels through Earth's atmosphere, including albedo, scattering, and absorption.
These phenomena play crucial roles in the Earth's energy balance and climate system.
## Albedo
Albedo is the fraction of sunlight that is diffusely reflected by a surface or object[9]. It is measured on a scale from 0 (complete absorption) to 1 (complete reflection)[9].
The Earth's overall albedo is approximately 0.29, meaning about 29% of incoming solar radiation is reflected back to space[12]. …
As solar radiation passes through the atmosphere, it interacts with particles and gases, leading to scattering and absorption processes.
### Scattering
Scattering occurs when particles or gas molecules redirect incoming solar radiation[10]. There are three main types of scattering:
1. Rayleigh scattering: Caused by gases, mainly N2 and O2[2].
2. Mie scattering: Occurs due to aerosol particles and cloud droplets[2].
3. Non Selective scattering: Affects all wavelengths equally[10].
Scattering reduces the amount of direct solar radiation reaching Earth's surface but increases diffuse radiation[1].
### Absorption
Absorption is the process by which solar radiation is retained by a substance and converted into heat energy[3].
Key aspects of atmospheric absorption include:
- Major absorbers: water vapor, carbon dioxide, ozone, and other trace gases[2]. (I agree with WV, but not the rest)
- Wavelength dependence: Different atmospheric constituents absorb radiation at specific wavelengths[6].
- Vertical distribution: About 3% of solar energy is absorbed in the stratosphere, primarily by ozone[5].
## Impact on Incoming Solar Radiation
The combined effects of albedo, scattering, and absorption significantly modify the incoming solar radiation:
- Approximately 70% of incoming solar energy is absorbed by the Earth system[5].
- 50% is absorbed by the Earth's surface (land and oceans)[5].
- 20% is absorbed by the atmosphere and
clouds[5].
- 30% is reflected or scattered back to space[5].
These processes are fundamental to understanding Earth's energy balance and play a crucial role in shaping our planet's climate system.