JULY 2019 C O R R E S P O N D E N C E 2181 CORRESPONDENCE Comments on ‘‘Is Condensation-Induced Atmospheric Dynamics a New Theory of the Origin of the Winds?’’ a,b a,b,f c a d A. M. MAKARIEVA, V. G. GORSHKOV, A. D. NOBRE, A. V. NEFIODOV, D. SHEIL, e b P. NOBRE, AND B.-L. LI a Theoretical Physics Division, Petersburg Nuclear Physics Institute, Saint Petersburg, Russia b U.S. Department of Agriculture–China Ministry of Science and Technology Joint Research Center for AgroEcology and Sustainability, University of California, Riverside, Riverside, California c Centro de Ciencia^ do Sistema Terrestre, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Brazil d Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Ås, Norway e Center for Weather Forecast and Climate Studies, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Brazil (Manuscript received 19 December 2018, in final form 27 May 2019) ABSTRACT Here we respond to Jaramillo et al.’s recent critique of condensation-induced atmospheric dynamics (CIAD). We show that CIAD is consistent with Newton’s laws while Jaramillo et al.’s analysis is invalid. To address implied objections, we explain our different formulations of ‘‘evaporative force.’’ The essential concept of CIAD is condensation’s role in powering atmospheric circulation. We briefly highlight why this concept is necessary and useful. 1. Introduction energy of wind (Makarieva and Gorshkov 2009, 2010; Makarieva et al. 2013b, 2014a). Jaramillo et al. (2018) critiqued our theory of Jaramillo et al. (2018) stated that CIAD modifies the condensation-induced atmospheric dynamics (CIAD). equation of vertical motion such that it violates Newton’s CIAD results from the difference between evaporation third law. This is incorrect: CIAD constrains the power and condensation. While most evaporation occurs at of atmospheric circulation; it does not modify ‘‘the ver- Earth’s surface, and is a slow, widely distributed process, tical momentum budget’’ nor any fundamental equations condensation in contrast occurs within the atmospheric of hydrodynamics. Furthermore, Jaramillo et al.’s (2018) volume and, depending on vertical air velocity, can be analysis of the equation of vertical motion is invalid. orders of magnitude more rapid than evaporation. In simplified form, water vapor with partial pressure py is added to the atmosphere at the surface and removed at 2. The equation of vertical motion the mean condensation height hg in air ascending with 23 21 Jaramillo et al. [2018, their Eq. (8)] write the equation vertical velocity w. The product pyw/hg (J m s ) gives of vertical motion as the rate of the release of available potential energy 23 ›p ›p py (J m ) equal to the rate of generation of the kinetic F 5 2 d 2 gr 1 F 1 2 y 2 gr 1 F z ›z d yd ›z y dy ›p f Deceased. 52 2 gr 1 F 1 F 5 ra , (1) ›z yd dy z Corresponding author: A. M. Makarieva, ammakarieva@ where az is the vertical acceleration of air; g is the ac- gmail.com celeration of gravity; and pd, py, and p 5 pd 1 py and DOI: 10.1175/JAS-D-18-0358.1 Ó 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses). Unauthenticated | Downloaded 09/27/21 07:28 PM UTC 2182 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUME 76 5 1 rd, ry, and r rd ry denote, respectively, the pressure equation of motion [Eq. (1)] into two ‘‘component’’ p and density r of dry air, water vapor, and moist air as a equations, for water vapor and dry air: whole. The terms grouped in each set of parentheses are ›p interpreted by Jaramillo et al. (2018) as ‘‘the forces on 52 y 2 1 5 1 ryazy ryg Fdy fe Fdy , (5) each component’’—dry air and water vapor. ‘‘Internal ›z forces’’ Fyd and Fdy are defined as ‘‘respectively the force ›p r a 52 d 2 r g 1 F , (6) of the vapor on the dry air and the force of the dry air on d zd ›z d yd the vapor,’’ which cancel because of Newton’s third law: Fyd 52Fdy. where azy and azd are vertical accelerations of water vapor Equation (6) of Jaramillo et al. (2018) gives the defi- and dry air. Our suggestion is supported by Jaramillo nition of the evaporative force fe as introduced by et al. (2018, p. 3307) interpreting fe [Eq. (2)] as ‘‘a force Makarieva and Gorshkov [2007, their Eq. (16)]: on the water vapor component.’’ If, as Jaramillo et al. (2018) assume, ‘‘the air parcel is not undergoing vertical accel- ›py py 5 5 f [2 2 , (2) eration,’’ azy azd 0 and Eq. (4) follows from Eq. (5) e ›z h y and Fdy 52Fyd. The problem with this assumed derivation is that Eqs. (5) where h [ RT/M g, R is the ideal gas constant, T is y y and (6) are incorrect. Separate equations of motion can temperature, and M is molar mass of water vapor. y be justified for such components of moist air as the gas and Force f quantifies the deviation of the vertical distri- e the condensate as they have distinct velocities (Makarieva bution of water vapor from equilibrium (discussed in the et al. 2017), but not for the various components of a next section). Since r 5 M N and, according to ideal y y y mixture of ideal gases that all move at the same velocity. gas law, p 5 N RT, where N is molar density of water y y y In the case of Eqs. (5) and (6), the error is to assume that vapor, fe [Eq. (2)] can also be written as ›pd/›z, the partial pressure gradient of dry air, acts ex- ›p 52 y 2 clusively on dry air, while the partial pressure gradient of fe ryg. (3) ›z water vapor ›py/›z acts exclusively on water vapor. Molecules of all gases adjacent to the considered unit Jaramillo et al. (2018) state that ‘‘if the air parcel is not volume of moist air collide and exchange momentum: undergoing vertical acceleration, then dry air and water vapor molecules outside the volume 5 collide with both dry air and water vapor molecules Fyd fe , (4) within it (Fig. 1a). The difference in the rates of these as defined by (6).’’ From this, they conclude that CIAD collisions above and below the volume determines the ‘‘includes Fyd in the vertical motion equation while vertical pressure gradient ›p/›z, which is an external omitting Fdy,’’ which represents ‘‘a clear violation of force acting on the considered air volume. The verti- Newton’s third law.’’ cal difference in the rates of collisions of water vapor This conclusion is not supported by evidence. First, molecules outside with any molecules within determines Jaramillo et al. (2018) did not quote any equation from ›py/›z, which is likewise an external force acting on the our works that would represent the alleged modified same air volume. Thus, when ›py/›z is perturbed, all air, equation of vertical motion. Jaramillo et al. (2018) in- and not just the water vapor, will accelerate (Fig. 1b). correctly attribute their Eq. (11), which is an adiabatic Since the external forces in Eqs. (5) and (6) are incor- version of raz 52›p/›z 2 rg 1 Fyd,toGorshkov et al. rectly specified by Jaramillo et al. (2018),Eqs.(5) and (2012). Everywhere in our works, the equation of ver- (6) are also incorrect as equations of motion: the sum of tical motion is raz 52›p/›z 2 rg; see, for example, the forces on the right-hand side of these equations, Eq. (15) of Makarieva and Gorshkov (2007), where taken per unit mass, is not equal to accelerations azy and raz 52›p/›z 2 rg 5 fe, and Eqs. (13) and (19) of, re- azd. Therefore, Fyd cannot be retrieved from the condi- spectively, Gorshkov et al. (2012) and Makarieva et al. tion azd 5 azy 5 0 and remains unspecified. With Fyd (2013b),whereraz 52›p/›z 2 rg 5 0 (hydrostatic equi- unspecified, Jaramillo et al.’s (2018) conclusion that librium). CIAD does not modify the equations of CIAD ‘‘includes Fyd in the vertical motion equation motion. while omitting Fdy’’ is meaningless. Second, while Jaramillo et al. (2018) characterize their analysis as ‘‘rigorous,’’ they do not explain how their key 3. CIAD and potential energy statement—Eq. (4)—was obtained. Indeed, Fdy and Fyd cancel and thus cannot be retrieved from Eq. (1).We Jaramillo et al. [2018, their Eqs. (6) and (7)] cor- speculate that Jaramillo et al. (2018) separated the rectly note that we used two different expressions for the Unauthenticated | Downloaded 09/27/21 07:28 PM UTC JULY 2019 C O R R E S P O N D E N C E 2183 FIG. 1. Momentum exchange among gas molecules (open circles: dry air; filled circles: water vapor; dashed frame denotes the considered unit volume). (a) The cartoon is a reminder that all types of molecules collide with each other (arrows show the chaotic velocities of molecular motion). (b) The gradient of water vapor is perturbed from the initial equilibrium state in (a) by an instantaneous removal of water vapor from the upper quarter of the vessel; the gradient of dry air is not perturbed; and within the unit volume, nothing changes either—in particular, interactions between the molecules remain the same.