Introduction

First uploaded on 2022/07/30
Last updated on 2024/07/19
Copyright(C)2022 jos <jos@kaleidoscheme.com> All rights reserved.

In the world of fluid dynamics and thermodynamics, it is believed that natural flows with large physical (space and time) scales transition to flows with smaller physical scales and are eventually converted to heat, which is random molecular motion. It is an irreversible process. Transitions of the energy spectrum in the opposite direction never occur. This is summarized as the second law of thermodynamics, and there is currently little research on phenomena that contradict this law, such as perpetual motion and the conversion of small-scale flows into large-scale flows.

However, there is one very major and important area of research being conducted on the possibility of small-scale flows creating larger-scale flows: this is the study of Dynamical Detrainment from cumulus clouds in climate prediction problems. Dynamical detrainment is a physical process in which mass/heat/water vapor is transported from the interior of a cumulus cloud to the surrounding atmosphere by the flow associated with the motion of the cloud.

[NOTE]
If you are uninitiated for Dynamical Detrainment at all, please see the page of What is Dynamical Detrainment.

Such transport from the interior of a cumulus cloud to the surrounding atmosphere is rarely a problem in so-called weather forecasting. This is because it is not a disaster-causing phenomenon such as severe precipitation or strong winds. However, it is a very important issue in climate prediction, known as "the problem of water vapor feedback to global warming". How water vapor, a greenhouse gas, is transported and distributed from the interior of cumulus clouds to large area of clear sky outside, and how it changes under a warmed condition, affects whether global warming triggered by an increase in atmospheric carbon dioxide will be accelerated or suppressed, and if so, to what degree. This is entirely determined by natural phenomena, with no human involvement, different from the amounts of carbon dioxide or methane in the atmosphere. It is therefore the subject of a purely scientific evaluation, not a political or economic one.

Conventional meteorological dynamics is mainly interested in the generation and resolution of atmospheric instabilities. These phenomena are often accompanied by severe precipitation, strong winds, and thunderstorms, and are therefore considered to be the focus of research as they are directly related to disasters. The behavior of mid-latitude cumulus clouds is a typical example. Recently, linear rain belt that bring strong precipitation can be predicted with high accuracy. The many successes in meteorology have provided strong motivation to apply the same techniques to climatology. It is perhaps natural to assume that the transport from the interior to the exterior of a cumulus cloud is also due to the intense dynamical motion associated with the cloud.

First of all, however, cumulus clouds in low-latitude region, which occupies a large area of the Earth's surface and is climatologically important, do not organize themselves into larger-scale disturbances under the influence of baroclinicity, as is the case with mid-latitude clouds. They develop in the form of isolated cumulus clouds. When we look at the phenomenon of isolated cumulus cloud from the perspective of fluid dynamics and thermodynamics, we can see it as the penetration of a hot, water vapor-rich thermal plume in the lower troposphere into the cooler, drier atmosphere in the upper troposphere. This is nothing more than the mixing of two non-uniform fluids into a uniform fluid. The thermal plume, which started out as a single large mass, breaks up into smaller vortices during the mixing process, and by the time it develops into a cumulus cloud, the physical scale of the individual motions occurring inside is very small. The lumpy/uneven pattern that appears on the cloud surface is indicative of the numerous small vortices. From this perspective, dynamical detrainment from an isolated cumulus cloud is a phenomenon in which these small-scale vortices generated in the mixing process are integrated and transformed back again to a larger flow out of the cumulus cloud. This raises the suspicion that they are considering a transition in the energy spectrum in a direction that violates the second law of thermodynamics. In other words, dynamical detrainment, like perpetual motion, is a thermodynamical phenomenon that should not occur. In fact, half a century has passed since the first papers on dynamical detrainment were published, and yet no clear answer seems to have been found to this question. Even if we spend another half century, dynamical detrainment will not be able to explain the transport from the inside to the outside of a cumulus cloud. In general, the motion of a fluid is governed and determined by phenomena of the same or larger physical scale. Shouldn't we look for the cause of net mass/heat/water vapor transport around a cumulus in the larger atmospheric field around the cumulus, instead of looking for the cause in the motion inside the cumulus, which has a smaller physical scale?

The physical process responsible for the net transport is Radiatively Driven Circulation (RDC), which we discovered twenty years ago. This web site describes in detail the basic concepts of RDC and the RDC scheme, a method for applying the RDC mechanism to real-time 3D atmospheric models. The RDC scheme is derived theoretically based on a few physical principles, rather than relying on parameter tuning as in the conventional DD methods. RDC has been confirmed to be dominant in the transport around cumulus clouds in vertical 2D model atmospheres. In addition, RDC acts to maintain relative humidity in the atmosphere under warming conditions. This provides a strong positive water vapor feedback that can explain the accelerated global warming currently occurring in the real atmosphere.

Our views have not changed at all in twenty years. Nor has there been a complete logical rejection of RDC. We have found that we ourselves need to be actively involved in RDC research in order to advance RDC research. However, without sufficient validation of RDC, it is difficult to generate new interest in the climatological research community through the basic theoretical work that we can do. We have therefore decided to present an RDC-based cumulus parameterization that can be applied to practical three-dimensional time-developing atmospheric models. But, with the current lack of acceptance of RDC by many researchers, it is difficult to submit a paper to a scientific journal for peer review. Even if it is accepted, the copyright must be revoked and we will not be able to protect RDC from illogical attacks. This would be repeating the experience of twenty years ago. It is difficult to stimulate RDC research in the usual way. Presenting the RDC parameterization as a company product is the last resort we have reached. By retaining copyright, we can at least correct misinterpretations and misrepresentations of RDC. We had no other choice. Thank you for your understanding.

Our aim is neither to convert all the researchers to RDC nor to become the majority. Our aim is to find people who are interested in RDC and to work together to advance RDC research. At the same time, however, we are always ready to drop the RDC theory when it is logically rejected to our satisfaction. Even if RDC is logically rejected, the arguments should be able to contribute to global warming predictions by providing new information and should not be wasted.

We are interested in working with people who are interested in RDC, and who are not bound to the existing authorities, conventions, or preconceptions. We invite you to contact us after carefully examining not only the main article A New Scheme of Cumulus Parameterization Based on RDC, but also Brief Considerations on RDC and References. The article What is Wrong with Dynamical Detrainment is especially recommended because it summarizes the critical issues of Dynamical Detrainment which is currently being studied primarily. Another article Two Types of Circulation in the Atmosphere is also recommended because it succinctly illustrates the difference between the two types of circulation that exist in the atmosphere; the Convectively Driven Circulation (CDC), which is assumed to be dominant in DD methods, and the Radiatively Driven Circulation (RDC). We seriously and sincerely hope that the RDC scheme will be widely tested. Thank you for understanding.