Autovariations And Feedback

It is convenient to consider the various elements of the earth/atmosphere system as separate entities, as has been done here. They are, however, quite intimately linked, and understanding the nature of these links is important—not only in the pure scientific study of the atmosphere itself, but also in the applied, interdisciplinary approach required for the study of modern global environmental problems. The elements and processes incorporated in the earth's energy budget and the atmospheric circulation, for example, are parts of a dynamic system, in which the components are sufficiently integrated that one change will automatically produce others. Such changes, produced through the activities of internal processes are called autovariations

(Trewartha and Horn 1980), and, in combination with feedback mechanisms, they may augment or dampen the effects of a particular change in the system. Lower temperatures at the earth's surface, for example, would allow the persistence of snow cover beyond the normal season. This, in turn, would increase the amount of solar radiation reflected back into space, causing surface temperatures to fall even more, and encourage the snow to remain even longer. Such a progression, in which the original impact is magnified, illustrates the concept of positive feedback. Rising temperatures may initiate negative feedback. One of the initial effects of higher temperatures would be an increase in the rate of evaporation from the earth's surface. Subsequent condensation of the water vapour in the atmosphere, would increase cloudiness, and reduce the amount of solar radiation reaching the surface. As a result, temperatures would fall again, and the initial impact of rising temperatures would be diminished. Ultimately, these changes in the earth's energy budget would be reflected in the general circulation of the atmosphere. Many current global issues—such as the intensification of the greenhouse effect, increased atmospheric turbidity and desertification—involve autovariations, and include positive or negative feedback in their development.

The Basic Survival Guide

The Basic Survival Guide

Disasters: Why No ones Really 100 Safe. This is common knowledgethat disaster is everywhere. Its in the streets, its inside your campuses, and it can even be found inside your home. The question is not whether we are safe because no one is really THAT secure anymore but whether we can do something to lessen the odds of ever becoming a victim.

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