Preprints
https://doi.org/10.5194/hessd-12-10921-2015
https://doi.org/10.5194/hessd-12-10921-2015
27 Oct 2015
 | 27 Oct 2015
Status: this discussion paper is a preprint. It has been under review for the journal Hydrology and Earth System Sciences (HESS). The manuscript was not accepted for further review after discussion.

Experimental evidence of condensation-driven airflow

P. Bunyard, M. Hodnett, G. Poveda, J. D. Burgos Salcedo, and C. Peña

Abstract. The dominant "convection" model of atmospheric circulation is based on the premise that hot air expands and rises, to be replaced by colder air, thereby creating horizontal surface winds. A recent theory put forward by Makarieva and Gorshkov (2007, 2013) maintains that the primary motive force of atmospheric circulation derives from the intense condensation and sharp pressure reduction that is associated with regions where a high rate of evapotranspiration from natural closed-canopy forests provides the "fuel" for cloud formation. The net result of the "biotic pump" theory is that moist air flows from ocean to land, drawn in by the pressure changes associated with a high rate of condensation.

To test the physics underpinning the biotic pump theory, namely that condensation of water vapour, at a sufficiently high rate, results in an uni-directional airflow, a 5 m tall experimental apparatus was designed and built, in which a 20 m3 body of atmospheric air is enclosed inside an annular 14 m long space (a "square donut") around which it can circulate freely, allowing for rotary air flows. One vertical side of the apparatus contains some 17 m of copper refrigeration coils, which cause condensation. The apparatus contains a series of sensors measuring temperature, humidity and barometric pressure every five seconds, and air flow every second.

The laws of Newtonian physics are used in calculating the rate of condensation inside the apparatus. The results of more than one hundred experiments show a highly significant correlation, with r2 > 0.9, of airflow and the rate of condensation. The rotary air flows created appear to be consistent both in direction and velocity with the biotic pump hypothesis, the critical factor being the rate change in the partial pressure of water vapour in the enclosed body of atmospheric air. Air density changes, in terms of kinetic energy, are found to be orders of magnitude smaller than the kinetic energy of partial pressure change.

The consistency of the laboratory experiments, in confirming the physics of the biotic pump, has profound implications for current mathematical climate models, not just in terms of predicting the consequences of widespread deforestation, but also for better understanding the atmospheric processes which lead to air mass convection.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
P. Bunyard, M. Hodnett, G. Poveda, J. D. Burgos Salcedo, and C. Peña
 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
P. Bunyard, M. Hodnett, G. Poveda, J. D. Burgos Salcedo, and C. Peña
P. Bunyard, M. Hodnett, G. Poveda, J. D. Burgos Salcedo, and C. Peña

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Short summary
Through physical experiments on 20 cubic metres of enclosed air in a structure consisting of two 5 m tall interconnected columns, water vapour condensation is seen to lead to uni-directional horizontal airflows. The findings support the physics underlying the controversial biotic pump theory. The conclusion is that large-scale deforestation will, through diminished cloud formation, have a devastating impact on intra-continental rain patterns, even leading to desertification.