Introduction

Main publication
(abstract)

Overview of the results

Comments and responses
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Anonymous (2006): General critique of biotic pump. www.biotic-regulation.pl.ru/pump/comm5.htm

The general idea is interesting and the concept of the water vapor recycling role has merit. The main problem is that the authors ignore a lot of important things that are known for decades (even century) about thermodynamics of the atmosphere with water vapor. They apparently do not know what is virtual temperature, potential temperature, saturated potential temperature, equivalent potential temperature, convective instability, available convective potential energy, skew-T diagram, in summary material that a good text in atmospheric thermodynamics has (eg Iribarne). It is fundamental that they read with attention and reformulate their writing taking existing thermodynamic knowledge into account. There are serious errors, as to say that up to now water vapor effect are not taken into account (evaporation) in the change of the lowering or rising of pressure (column weight). This is an absurd! It is clear that this has always been taken into account. The quantitative way to take that into account, as in the CPTEC model, is to use the virtual temperature variable, instead of temperature, that takes into account that the air is a mixture of gases and one of them, water vapor, presents a spatial and temporal variability, therefore a density, and thus a pressure has to reflect that. The central physical concept that lack of hydrostatic equilibrium of water vapor do not hold because water vapor molecules are mixed in the atmosphere and it is only meaningful to talk about hydrostatic equilibrium (the vertical pressure gradient force balanced by the gravity force) for the atmospheric composition as a whole and this approximation, extremely useful in meteorology, is only valid for very large scale movements, where horizontal dimensions >>> than the vertical dimension.

I do not think that a new mechanism has been found. The central idea is interesting and deserve publicizing, but they will have a sizable challenge in correcting conceptual errors.

Another suggestion that can be given to the authors is that they use simple conceptual models of idealized situations. In an imaginary planet, with idealized geometries of continents, oceans, forests, etc., they could develop simple conceptual models of the water vapor flux, water balance and evaporation. Such conceptual models were always very useful and physicists are masters on that. I think that they have tried to apply directly an extremely simplified model to explain nature and there it becomes much more difficult. It is worthwhile to suggest them that they should change their focus and stay only with conceptual models of an idealized vegetated planet, with simple fluxes and geometries. Such a paper would evoke the interest of groups operating complex models to test the ideas.

Makarieva A.M., Gorshkov V.G. (2006): Response to anonymous critique of biotic pump regarding the role of water vapor in meteorology. www.biotic-regulation.pl.ru/pump/comm5.htm

It is not claimed in our work that "up to now water vapor effect are not taken into account (evaporation) in the change of the lowering or rising of pressure (column weight)". In fact, we stress that the effect of the non-equilibrium distribution of water vapor is WELL-KNOWN. It would be indeed absurd to say that water vapor itself has been unknown in atmospheric and meteorological science. The formal apparatus involving potential temperature referred to in the comment, has indeed been used to calculate the amounts of water vapour in the atmosphere. What is stated in the work is that the observed properties of the water vapor distribution have not been appreciated in its importance, that is, no conclusions about the existence of the evaporative force were made from this knowledge.

The comment says: "The central physical concept that lack of hydrostatic equilibrium of water vapor do not hold because water vapor molecules are mixed in the atmosphere and it is only meaningful to talk about hydrostatic equilibrium (the vertical pressure gradient force balanced by the gravity force) for the atmospheric composition as a whole."

The hydrostatic equilibrium of the atmospheric composition including various gases (as a whole) is impossible. It counteracts the basics of gas physics. It is similar to saying that if you take two jars with different gases but having equal pressure and make them contact each other, nothing will happen because the pressures are equal. In reality, however, the gases will mix up quickly, and in the resulting stationary state not only pressures, but also the concentrations of gases in the two jars will be the same.

The same is true for the gravitational field, where the stationary stable state is the state when each gas is distributed along the vertical with its own scale height determined by its molecular mass. The excessive pressure of one gas cannot compensate the insufficient pressure of another. As we mentioned in the pre-print, this physical principle is responsible for the phenomenon of osmosis: when you bring in contact two solutions (or gaseous mixtures) of the same total pressure but with different concentrations of the compounds, the concentrations start to equate. But, if there is a membrane which prevent compound X to move from one solution to another, while the second compound Y can move freely, the resulting stationary case will be when compound Y (e.g. water), trying to equate its concentrations on both sides of the membrane, will accumulate on one side of this membrane in excess, producing the uncompensated pressure. The force associated with this effect is huge, tearing in pieces metallic ships and allowing seeds to effectively suck in the ambient water.

At the same time, if there were no membrane, the concentrations of both solutions would equate producing no pressure gradient.

In the atmosphere, the role of membrane which differently treats the different (condensable and non-condensable) air constituents is played by the vertical temperature gradient. Through condensation governed by the temperature-dependent Clausius-Clapeyron law, it does not allow water molecules to move upward in quantities sufficient for establishment of the hydrostatic equilibrium. At the same time it does not impede vertical propagation of the non-condensable air constituents. So, in the stationary case, the evaporative force persists and is large enough to generate the atmospheric circulation.

As far as the water vapour mixing ratio is very small, one can say that atmosphere as a whole is in hydrostatic equilibrium (to the accuracy of this few per cent). However, it appears that namely these few per cent determine the major processes in the atmosphere.

We do claim that this effect has not been known in the meteorological and atmospheric science. Even the simple fact that the scale height of atmospheric water vapor (2 km) as compared to the much larger scale height of other air gases (8 km) can be easily calculated from the Clausius-Clapeyron equation using the observed vertical temperature lapse rate, is missing from the meteorological textbooks, where it is presented merely like an empirical generalization. Only in 1995 Weaver and Ramanathan noted (parenthetically) that these 2 km could indeed be retrieved in this way. And no one has ever mentioned the vertical force associated with the non-equilibrium vertical water pressure gradient.

Since these effects are as real as is the gravitational field and the observed temperature lapse rate on Earth, there is in our view no reason to describe them for some idealized planet.