BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:A tale of two paradigms\, with remarks on unconscious assumptions 
 - Prof Michael E McIntyre (University of Cambridge)
DTSTART:20140115T160000Z
DTEND:20140115T170000Z
UID:TALK49873@talks.cam.ac.uk
CONTACT:Alison Ming
DESCRIPTION:Haurwitz Memorial Lecture first given to the American Meteorol
 ogical Society\n\nSince the writing of Haurwitz's 1941 classic "Dynamic Me
 teorology"\, our understanding of global-scale atmospheric circulations\, 
 jet formation and other fundamentals has been revolutionized by two mutual
 ly-relevant paradigms that took over from the old turbulent\nmomentum-mixi
 ng paradigm.  Both paradigm changes went in fits and starts over the best 
 part of a century.  There was no "Einstein moment" after which everything 
 became clear.  The first of the new paradigms says that the global-scale a
 tmosphere is radiation-stress-dominated.  That is\, large-scale momentum t
 ransports are dominated not by turbulent but by wave-induced momentum tran
 sports.  The second paradigm -- I'll call it the "inhomogeneous PV-mixing 
 paradigm" -- can be traced back nearly a full century to seminal work by G
 . I. Taylor yet even today is still being evolved\, debated\, and clarifie
 d\, as computing power improves.  It says not only that potential vorticit
 y (PV) tends to be mixed along stratification surfaces\, but also that the
  mixing tends to be spatially inhomogeneous.  Indeed\, observed phenomena\
 , including the observed structure of strong jets\, show that the spatial 
 inhomogeneity is often strong.  It lies entirely outside the scope of stan
 dard homogeneous-turbulence theory. The very phrase "turbulence theory" is
  a misnomer because the reality is often a highly inhomogeneous wave-turbu
 lence jigsaw\, with turbulent and wavelike regions closely adjacent and in
  dynamical symbiosis.  The jigsaw fits together dynamically as well as geo
 metrically.  Without the wave part one cannot begin to understand even gro
 ss angular-momentum budgets.  The simplest idealized example that illustra
 tes the symbiosis is not homogeneous-turbulence theory but\, rather\, the 
 nonlinear Rossby-wave critical layer theory first fully developed by Stewa
 rtson\, Warn\, Warn\, and Haynes.  A further payoff from these insights ha
 s been a breakthrough in understanding the Sun's internal differential rot
 ation.\n
LOCATION:MR15\, Centre for Mathematical Sciences
END:VEVENT
END:VCALENDAR