Introduction - Severe Convective Storms and Tornadoes: Observations and Dynamics - page 2

precipitation distribution (with little regard for cloud particle type or precipitation
type) in severe convective storms. The reader is directed elsewhere for detailed dis-
cussions of cloud microphysics and precipitation formation, including the
formation of large hail (e.g., Knight and Knight, 2001), the hydrological con-
sequences of excessive rainfall (i.e., flooding), and cloud electrification and its
consequences (e.g., Williams, 2001). Forecasting techniques using numerical
models initialized by observational data are also not covered in much detail, in
part because at the time of this writing there is a flurry of activity using data
assimilation techniques that is in a state of rapid flux and, consequently, attempts
to detail them might not be useful, since the art and science of data assimilation
are changing so rapidly.
The purpose of this textbook is to summarize what we have learned in
approximately the last half-century about the kinematics and dynamics and, to a
lesser extent, the thermodynamics of severe convective storms. I do not use the term
''thunderstorm'', because it is possible that a severe convective storm does not
produce lightning and I would not want to exclude this class of storms from dis-
cussion. In addition, while the adjective ''convective'' simply denotes the
movement of air in general, we generally use the adjective ''convective'' to denote
small-scale movements of air in deep cumulus clouds or cumulonimbus clouds.
Advances in observing systems, particularly in radars, and advances in
computer technology and numerical modeling techniques have stimulated and
made possible fruitful studies of the structure and dynamics of severe convective
storms. Through the analysis of observational data (from both quantitative meas-
urements and from visual observations) and the results of controlled numerical
experiments, the fundamental processes responsible for determining the convective
storm type and the severe weather associated with each type of convective storm
have been identified.
After a brief history in this chapter of the major field programs and numerical
simulation experiments aimed at understanding the physical processes responsible
for severe convective storms is given, the dynamical and, to a much lesser extent,
the thermodynamic frameworks used to diagnose the behavior of severe convective
storms are discussed mathematically and explained physically in Chapter 2.
Thermodynamics is given short shrift because the details are mostly important for
numerical modelers and numerical modeling is not a major focus of this topic.
Students and readers are referred elsewhere (e.g., Emanuel, 1994) and to many
journal articles (see the reference lists for specific works) for further discussions on
thermodynamics. Also, it is assumed that the reader has some knowledge of radar
meteorology. Some additional information, however, is embedded within the main
body of the text on the maturing area of polarimetric radar technology and its
applications to severe convective storm studies.
The author believes that students will gain an increased appreciation for the
theory after they have become aware of some of the major problems and solutions
to them that have been grappled with and proposed by scientists, engineers, com-
puter scientists, and amateur meteorologists and have become more acquainted
with the actors involved in the scenes of the theater of severe storm meteorology.