Climatologia da Região Norte : introdução à climatologia dinâmica : subsídios à geografia regional do Brasil

Resumo

Since the European has discovered the Amazon region, four hundred years ago, his opinion about the climatic conditions of that region has varied from out to out. Sometimes he exalts, sometimes he condemns that huge world of jungle and. rivers.

The Amazon region, in Brazil, comprises a wide plain situated a little above the sea level, having its northern part crossed by the equator circle. It constitutes a region of regular contact between the atmospheric circulation systems of the north and south hemispheres. From these circumstances is derived their principal climatic characteristics: hot climate, humid or super-humid, of equatorial type.

Taking into account the temperature regime, all the region has a hot climate, once a mean temperature over 2°C is maintained all the months. It is true that in the southern areas of this region, especially the southwest, is common to verify abrupt and high decrease of temperature in winter, when an intense polar anticyclone is spread over the area. However, in view of the continuous high temperatures, and considering that the conditions above mentioned are so rare, these conditions don't affect in a significant way the monthly averages, in such a manner that determine a distinct climatic domination in this area, where the thermic amplitude is very low, mainly when we compare with the diurnal amplitude, this being very important.

Considering the humidity regime with the existence or not of a dry season, we verify that this domination of a hot climate have well differentiated. areas which determine three climatic sub-dominions: super-humid, without dryness; humid, from one to two or three dry month; and semi-humid, from four to five dry months. This last one, in opposition of the others comprises a relatively small area. The geographical delimitation of these areas is being prejudiced by the scarceness of weather stations in this region.

If the lack and scarceness of weather stations is not sufficient to put in doubt the Amazon climate as for its conditions of hot and super-humid or humid, the more dense jungle and hydrographic net of the Earth, as their remarkable natural consequences, besides reasons of economic and politic order, have contributed to make the Amazon climate one of the less known, considering its peculiar characteristics. This has originated a series of concepts, partly wrong and even false of its climatic peculiarities, some of them are treated in this paper.