Innsbruck University

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Seven sins in dynamical meteorological education
The mathematics is always correct, the
computers are given the right equations, but the
explanations do not only contradict Nature but
also the mathematics they are supposed to
illuminate
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Seven sins in dynamical meteorological education
Professor Richard Reed, Univ. Of Seattle
1988 -Our understanding of the cyclogenesis
process has increased tremendously during the
last 40 years at least the computers seem to
understand!
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1. Air passing mountains
Although this conceptual model seems to work
well for westerly flow over topography, an
attempt to apply it to easterly flow quickly
leads to an absurdity. Prof. James Holton, Bull
AMS 1994
4
? lt 0
North higher f
? lt 0
? 0
South lower f
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2. Group velocity The energy is the atmospheric
flow is moving much faster downstream than the
individual waves
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James R. Holton, Fourth edition, 2004
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3. The Rossby Wave -I have never understood
what a Rossby waves is Professor Harold
Jeffreys on his deathbed 1987 Lunch discussion
at ECMWF 1995 Scientist -How is the weekend
going to be? AP -Fine, a Rossby wave is seen
coming in! Scientist -But you cant see Rossby
waves??
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A very common misunderstanding This is NOT a
Rossby wave!
low ? high f
?f?const
high ? low f
but a Constant Absolute Vorticity Trajectory!
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4. The Coriolis Effect -The serious students
should rebel against theories that have been
repeatedly shown to be seriously
incomplete! Professor W.M.Davis on the
explanation of the Coriolis effect in a speech
at the Royal Meteorological Society in 1899
(QJRMS 1899)
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Joseph Bertrands 1847 simplified derivation
of the Coriolis effect Two
common errors compensate each other
?
R
?R
?S
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5. Angular momentum Hadleys erroneous
explanation yielded excessive winds (50-80 m/s),
the correct concept of angular momentum yields
the double!
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The problem with angular momentum conservation
Angular momentum conservation does not need
information about the speed which the ring must
be displaced in order to reach as far north as
30? latitude without being turned by by the
Coriolis force.
130 m/s
The initial impetus must give an initial
poleward speed of exactly those 130 m/s which at
30? latitude is pointing eastward
What prevents any excessive winds from developing
is not friction, but pressure gradient forces
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6. Geostrophic adjustment The common
visualization is not only wrong, the teachers
miss chances to link to jet streams, both
nocturnal and upper tropospheric
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The school book image of geostrophic adjustment
in a constant pressure field
Low pressure
Vg
High pressure
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7. Indirect circulation and negative
work Textbooks ignore almost half of the
energetic processes in the atmosphere
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The energy budget
P
K
F
This is how the energy conversions in the
atmosphere is often portrayed - as an
irreversible process
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• So
• The same physical-dynamic processes can often be
  described by different mathematical formalisms
  
  
• The text-books authors do not always chose the
  most pedagogic mathematical formalism
• Whilst their mathematical derivations are always
  correct, this is not always the case for their
  interpretation of the mathematics

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