25 October 2010 [Publications]
Where do winds come from?

A new theory on how water vapor condensation influences atmospheric pressure and dynamics

Makarieva A.M., Gorshkov V.G., Sheil D., Nobre A.D., Li B.-L.

now up for public discussion at ACPD:


According to The Economist, the biotic pump theory stating that natural forests drive winds to sustain the water cycle on land has caused "a stir" in Western academia. Indeed, last time it was in the end of the 17th century (see Halley 1686) that a physical driver of winds was proposed. That time it was differential heating (the statement that the warm air rises being lighter than cold air). This idea became the consensus regarding the causes of atmospheric motion that has lasted over three hundred years. However, this consensus had formed long before the kinetic theory of gases was formulated. This fundamental theory revealed that gas pressure depends not only on temperature, but also on the number of gas molecules in a unit volume. Phase transitions of water (condensation and evaporation) namely change these numbers. Thus, spatial gradients of the intensity of condensation/evaporation are to be associated with air pressure gradients that cause the air to move. (By consequence, natural forests known for their high evaporation potential become a major player in atmospheric circulation.)

Remarkably, the effects of condensation/evaporation on air pressure via removal/addition of vapor molecules have managed to escape wide attention for a long time. This to such a degree that, as documented in our paper, there is now a confusion among scientists as to whether condensation increases or reduces moist air pressure. In other words, even the sign of the effect, let alone its magnitude, remains unclear to many meteorologists. This is despite recognition that the lack of theoretical concepts to treat moist effects is a major obstacle for the development of the atmospheric circulation theory (Schneider 2006 p. 682).

In the above paper just made available for public discussion at the Atmospheric Chemistry and Physics Discussions journal of the European Geosciences Union (EGU), we review recent knowledge on the dynamic effects of the phase transitions of water on air circulation and advance the physical foundations of the biotic pump theory in all its integrity. We want the new theory to be scrutinized openly, widely and deeply, and we are ready to invest efforts to clarify and defend our findings in public in the coming weeks. We hope that the EGU platform will be a guarantee that the discussion, including criticisms, will be constructive and of essence.

Please, feel free to join the commentators or to encourage to comment those scientists who you believe might be interested in the topic. The discussion is open until 10 December 2010 during which time the authors will be available to share their insights, for what they are worth, into this really exciting question: Where do winds come from?

Some very relevant discussions are currently taking place here:

Modeling the Basics, A mathematical summary of condensation in climate models
Momentary lapse of reason
Where do winds come from?
hosted by Jeff Id at the Air Vent

Water Vapor Mischief
hosted by Dr. Judith Curry at Climate Etc.