To most people, our weather appears to be a random and chaotic phenomenon.
Although there are obvious diurnal and seasonal cycles, our day-to-day weather
continues to be perceived as being quite unpredictable. However, a careful
investigation of weather charts and satellite photographs shows that there are
in fact well defined and coherent systems that are responsible for much
of our weather. The existence of a coherent system embedded in an otherwise
chaotic fluid is indicative of the existence of a dynamical instability in the
fluid. The instability is responsible for a bifurcation in which the fluid
changes from dynamical regime to another. My research is centered upon
identifying and understanding the dynamical processes responsible for these
bifurcations.
One of the most important of these systems is the frontal cyclone (see Figure). Although they were first identified in the middle of the nineteenth
century, it has only been recently that my research has led to the
identification of the dynamical process responsible for their development.
Research is continuing into this important new bifurcation which we have called
the cyclone-scale mode of baroclinic instability. The preferred region
for the development of this new instability are the regions of enhanced thermal
gradients known as frontal zones. These zones are the result of
large-scale atmospheric circulation that acts to concentrate the initially
uniform equator-to-pole temperature contrast into a narrow zone. The cyclones
that develop via this mechanism draw on the potential energy stored within the
front.
