From the climatic point of view, Brazil falls entirely within the tropical area; and precisely this tropicality constitutes the most marked character of its geography due to the effects it has on the landscape as well as on men and their activities. However, there are considerable differences from region to region. On the contrary, a first distinction can be made by recognizing a humid equatorial climate in the Amazon region, a subequatorial climate in the immediately S belt and a two-season tropical climate, more or less rainy, in the rest of the country, whose southernmost sector now makes one foresee the temperate climate (subtropical climate): this wide range of zonal conditions is due to the extension of the country, which is between 5º16´ N and 33º45´ S. As for the mechanisms that determine the climate, it is necessary to take into account the conformation of the territory, which is open, devoid of high mountain ranges and therefore largely exposed to the Atlantic, from which the air masses that bring rainfall come. In the Amazon region, located in the belt of intertropical convergences, this contribution is due to NE and SE trade winds, the effects of which add up giving rise to the equatorial conditions that make this region one of the wettest and rainiest areas on Earth, with annual rainfall values that are around 2000 mm on average and with temperatures almost constant, around 26 ºC. However, even in the Amazon there is an attenuation of the rains which occurs in the months of the austral winter (July-September), i.e. at the maximum zenitation of the Sun in the northern hemisphere. In this same season, the tropical continental surfaces are dominated by anticyclonic formations which maintain stable conditions and which are therefore responsible for the two-season climate of much of Brazil. According to cheeroutdoor, the dry season, which in the Amazon is very ephemeral and relative, to the S of it becomes marked and lasts up to six months. Rainfall occurs mostly in the austral summer months, from November to March, and brings about 1500 mm of rain per year. Temperatures, especially in the internal part where continentality is more accentuated, also vary a lot, with temperature variations annual up to 7-8 ºC and with daily temperature variations reaching 15 ºC on the southernmost internal plateaus. In Brasília, however, where the altitude contributes to significantly lowering the averages, it goes from 22 ºC in January to 19 ºC in July. Higher values are recorded on the coast, where the mitigating effect of the sea is felt: in Rio de Janeiro it goes from 27.5 ºC in January to 23 ºC in July. In the coastal region, rainfall is again high and this is because the high continental slopes have a capturing effect on the Atlantic humid air masses; Here there is a monsoon- like climate, with total rainfall that exceeds even 2000 mm per year on the reliefs. An exceptional area is the whole Northeast (Nordeste), a region which is set back from the prevailing direction of the Atlantic winds and which therefore has a tropical climate that tends to be dry, with in any case occasional, irregular rainfall, which often leads to critical conditions. In certain areas of the São Francisco basin, 500 mm per year are not reached; the temperatures reach particularly high values here.
TERRITORY: ENVIRONMENT. ECOLOGY
Starting from the 1960s, a process of occupation of low human density territories began, in particular the Amazon basin. This process, guided by precise geopolitical objectives, was based on the use of advanced technologies to create, in the pioneering fringes, an infrastructural and urban network that could allow the exploitation of the immense hydroelectric, mining, agricultural and livestock resources. Thus began a penetration into the forest and savannah areas that profoundly altered the natural balance: apart from the cutting-fire technique, which has long been used by farmers and ranchers, the open spaces for the construction of new roads and centers inhabited, also resorting to the use of powerful chemical means, they have determined an environmental impact that is difficult to control, in which indigenous populations have been heavily involved. The conversion of huge wooded areas into plantations for the cultivation of cocoa and eucalyptus (a non-endemic species) and, more recently, of soy (due to the expansion of farming) have caused a reduction in the extent of Brazilian forests, which occupy 61.2% of the territory. Deforestation, which in the period 2003-2004 alone affected an area of over 26,000 km², constitutes a serious threat to the species that populate the scrub; some of these are also subject to illegal trafficking. The country has high rates of pollution of the air and water not only in the big cities and urban agglomerations of Rio de Janeiro and São Paulo but also in the localities of extraction and processing of minerals. Here the contamination of the soil has caused and continues to cause an impoverishment of the land and the loss of their productivity. All this has aroused a vast movement of opinion, on an international scale, whose effects seem to have been translated, at the end of the century. XX, in a greater attention of the Brazilian government to ecological issues. Since the early 2000s, members of the Sem terra Movement and other organizations have committed themselves to give further resonance to the country’s environmental issues, protesting against the reduction of the protected Amazon area and against the indiscriminate exploitation of resources; the disputes of June 2008 led to the occupation, among other things, of thermoelectric power plants, refineries, industrial plants and plantations. In recent years, the government has launched an environmental protection plan, with the establishment of special bodies for the protection of renewable resources and the creation of numerous parks and reserves: in 2000 a single system for the conservation of heritage was established nature (SNUC) within the Federal Authority for the Environment and Renewable Natural Resources (Ibama) of the Ministry of the Environment. In fact, however, only 26% of the Brazilian territory is formally protected and within the national system there are units with integral protection and units intended for sustainable use. The first includes 58 national parks and numerous biological, natural and ecological reserves; in the second, other types of areas such as national forests, wildlife reserves, etc. There are also 19 natural and cultural sites reported by UNESCO, of which 7 are world natural heritage of humanity. The first, the Iguaçu National Park, was created in 1986; this was followed by the Atlantic Forest – Southeast Reserves (1999); the Atlantic Forest Reserves the Costa della Scoperta (1999); the Protected Area of the Central Amazon (2000, 2003), extension of the Jaú National Park; the Pantanal Conservation Area (2000); Ilhas Atlanticas brasileiras: Fernando de Noronha archipelago and Atol das Rocas (2001); the Chapada dos Veadeiros and Emas National Parks (2001).