Introduction - The Global Climate System: Patterns, Processes, and Teleconnections - page 9

of action or a series of changes. In the milieu of climate, process may be regarded
as a continuum of energy flow wherein available energy is utilized to maintain
the climate system. The resulting global and local energy and mass budgets
eventually provide the key to ongoing processes. Background Box 1.1 provides
an example of the standard symbols used to depict energy flows in the environ-
ment and the relationship to the heat budget. Changes in energy flows then lead
to changes in the nature of a climate and its resulting impact upon the human
environment. Such is considered in a number of ways in this work. As already
noted, the human response to changes over the last 1000 years is considered a
temporal pattern. It also represents a change in the processes resulting in that
climate. Another area where change is seen is in the urban environment. The
buildings that comprise a town or city create conditions that result in a totally
modified energy budget. The construction of an environment of cement and
macadam results in changing moisture flows and patterns (Bonan 2002 and
Chapter 7 ). Urban climatology has become a major area of specialization.
One result of the intensive study of process is the development of the concept
that any climate process that occurs at a given location does not vary or change
independently of other, often far distant, processes. This has led to an area of
research that deals collectively with teleconnections.
1.2.3 Teleconnections
Teleconnection is a term used to describe the tendency for atmospheric circula-
tion patterns to be related, either directly or indirectly, over large and spatially
non-contiguous areas. The AMS Glossary of Weather and Climate (Geer 1996 )
defined it as a linkage between weather changes occurring in widely separated
regions of the globe. Both definitions emphasize a relationship of distant pro-
cesses. However, the word ''teleconnection'' was not used in a climate context
until it appeared in the mid 1930s ( ˚ ngstr¨m 1935 ), and even until the 1980s was
not a commonly used term in the climatic literature.
As stressed throughout this topic, teleconnections are often associated with
atmospheric oscillations. Any phenomenon that tends to vary above or below a
mean value in some sort of periodic way is properly designated as an oscillation.
If the oscillation has a recognizable periodicity, then it may be called a cycle, but
few atmospheric oscillations are considered true cycles. This is illustrated by the
early problems in predicting the best-publicized oscillation, the Southern
Oscillation and El Ni˜o (Chapter 2 ). Were this totally predictable then many
of its far-reaching impacts could be forecast.
1.2.4 People and climate
The most important practical reason to understand the climate system is the link
with people, their activities, and their decision making. The relationships between