General Systems Theory Concepts in Atmospheric Flows - Rain Formation in Warm Clouds: General Systems Theory - page 7

of warm air upward and cold air downward analogous to superfluid turbulence in
liquid helium (Donelly 1998 , 1990 ). The convective growth of a large eddy in the
ABL therefore occurs by vigorous counter flow of air in turbulent fluctuations,
which releases stored buoyant energy in the medium of propagation, e.g., latent heat
of condensation of atmospheric water vapor. Such a picture of atmospheric convec-
tion is different from the traditional concept of atmospheric eddy growth by diffu-
sion, i.e., analogous to the molecular level momentum transfer by collision (Selvam
and Fadnavis 1998 ; Selvam 1990 , 2005 , 2007 , 2009 , 2011 , 2012a , b , 2013 ).
The generation of turbulent buoyant energy by the microscale fractional con-
densation is maximum at the crest of the large eddies and results in the warming
of the large-eddy volume. The turbulent eddies at the crest of the large eddies are
identifiable by an MCI that rises upward with the convective growth of the large
eddy during the course of the day. This is seen as the rising inversion of the daytime
planetary boundary layer in echosonde and radiosonde records and has been identi-
fied as the entrainment zone (Boers 1989 ; Gryning and Batchvarova 2006 ), where
mixing with the environment occurs.
The ABL contains large eddies (vortex rolls) which carry on their envelopes
turbulent eddies of surface frictional origin (Selvam and Fadnavis 1998 ; Selvam
1990 , 2005 , 2007 , 2009 , 2011 , 2012a , b , 2013 ). The buoyant energy production by
microscale-fractional condensation (MFC) in turbulent eddies is responsible for the
sustenance and growth of large eddies.
In summary, the buoyant energy production of turbulent eddies by the MFC pro-
cess is maximum at the crest of the large eddies and results in the warming of the
large eddy volume. The turbulent eddies at the crest of the large eddies are identifi-
able by a microscale-capping inversion (MCI) layer which rises upwards with the
convective growth of the large eddy in the course of the day. The MCI layer is a
region of enhanced aerosol concentrations. The atmosphere contains a stack of large
eddies. Vertical mixing of overlying environmental air into the large eddy volume
occurs by turbulent eddy fluctuations (Selvam and Fadnavis 1998 ; Selvam 1990 ,
2005 , 2007 , 2009 , 2011 , 2012a , b , 2013 ). The energy gained by the turbulent eddies
would contribute to the sustenance and growth of the large eddy.

1.4 Large Eddy Growth in the ABL

Townsend ( 1956 ) has visualized the large eddy as the integrated mean of enclosed
turbulent eddies. The root mean square (r.m.s) circulation speed W of the large eddy
of radius R is expressed in terms of the enclosed turbulent eddy circulation speed w *
and radius r as (Selvam and Fadnavis 1998 ; Selvam 1990 , 2005 , 2007 , 2009 , 2011 ,
2012a , b , 2013 ).

2
= π

r
R w

2 2

W

* .

(1.1)