The Climatic Significance of Meridional Circulation
Even though the general circulation pattern on the earth’s surface is principally zonal and not meridional, yet the meridional component of the surface wind system is very significant in the latitudinal heat balance of the earth.
According to Kendrew, the most effective channels of meridional exchange of heat and momentum are made available by the pressure irregularities as well as the high and low pressure centers. The areas of convergence and divergence play dominant roles in meridional circulation.
It may be noted that intertropical convergence zone is the most important and uninterrupted belt of convergence on the surface of earth. In the subtropical high-pressure belt there are numerous areas of divergence which make significant contribution to meridional circulation.
Areas of strong convergence and divergence of mean surface wind over the oceans produce innumerable complexities in the climates of the world. It is the closed centers of high and low pressure which virtually control air movement around them.
This results in the formation of many cellular circulations, some of which are cyclonic, while others are anticyclonic. These cellular circulations are superimposed on the zonal airflow pattern on the earth’s surface. Despite the intricacies of the circulation pattern the zonal circulation predominates.
The areas of divergence and convergence are known as centers of action, for it is along boundaries that most of the cyclones and anticyclones move out from one region to another.
