CLIMATE. – Extended approximately from 15 ° to 33 ° of lat. N, Mexico is cut in half by the Tropic of Cancer and is placed in the domain of tropical and subtropical climates. The effects of latitude, however, are largely modified by the altimetry and the arrangement of the reliefs. The annual temperature range increases from S to N: it is only 3.5 ° C in Salina Cruz, on the Gulf of Tehuantepec (16 ° 12 ′ lat.), 6.4 ° C in Mexico City (19 ° 30 ′ Lat.), 10 ° C in Tampico (22 ° 13 ′ lat.), 13.5 ° C in Matamoros (25 ° 52 ′ lat.) And 20.2 ° C in Ciudad Juárez (31 ° 40 ′ Lat.). The thermal differences become more pronounced especially with the variation of the altimetry. Already H. Cortés distinguished three thermal zones, which have become classic: tierras calientes (“Hot lands”), up to 600-700 m of altitude, with an average annual temperature of over 22 ° C: cocoa, banana, sugar cane and cotton thrive there; tierras templadas (“temperate lands”), between 600-700 m and 1600-1700 m, with an average annual temperature of 15-22 ° C: sugar cane, but above all coffee, is grown there, alongside corn and beans; tierras frias (“cold lands”), above 1700 m, where the average annual temperature is below 15 ° C and frosts are frequent: corn and wheat dominate here, while barley and potato meet up to 3200 m. Above an area of forests and pastures that can reach 4000 m, there are the tierras heladas (“frozen lands”): the limit of permanent snow is at 4700-4800 m.
The tropical Mexico in summer is hit by humid air coming from the Gulf of Mexico (NE trade wind), with abundant rains from late May-June to September-October. Disastrous cyclones often form at the beginning and in the middle of this period. The maximum rainfall is recorded in the coastal plain on the Gulf of Mexico and on the eastern slopes of the sierras, where the annual quantity exceeds 1500 mm (up to over 4000 mm to the S). The Pacific coast is reached, always in summer, by periodic monsoon winds, which trigger abundant rainfall, except to the North of the Tropic of Cancer. In the plains and sheltered basins (Sonora, Sinaloa, Baja California), the amount of precipitation is very modest and irregularly distributed. Cyclones (chubascos) that hit the southern and western coasts of Mexico are usually less violent than Atlantic cyclones.
In winter, the side of the Gulf of Mexico can be reached by northerly winds, cold and dry (nortes), which cause frosts on the highlands and in the plains, and more or less long periods of drought. The peaceful facade, protected from the humid trade winds and nortes, is generally arid; only the Tijuana region in northern Baja California has Mediterranean-type winter rains. The whole interior, closed to winds, receives scarce quantities of rain (approx. 500 mm per year, to the S), which decrease towards the N up to 300-400 mm; there is less than 200 mm in the coastal region of the Vermilion Sea and less than 100 mm in central Baja California.
FLORA. – The flora of Mexico, rich and varied, is characterized by a good number of endemics. In the coastal areas, the humid tropical forest succeeds a belt of dunes with characteristic vegetation. Moving away from the sea, one encounters savannas with giant grasses (bamboo and other genera), Ciperaceae, Tree ferns, Cicadaceae, Mimosa pudica etc. Even the temperate zone has a rich and varied flora, with ferns, palms and many species with brightly colored flowers: in the lower band evergreen oaks grow, in the upper deciduous oaks on which various Loranthus aboundand epiphytes and copious climbers. A particular region is that of the agaves, with several species, together with arborescent Cactaceae and Gigliacee. The slopes of the mountains of central and southern Mexico, up to 4000 m, are covered by forests of oaks and conifers, some gigantic, such as Taxodium mucronatum. Above, juniper bushes and grassy pastures up to 4800 m. From Mexico come many species cultivated in the gardens of Europe. For Mexico geography, please check franciscogardening.com.
FAUNA. – The fauna is made up of elements from the sonoran region and elements from the Mexican sub-region (from the neotropical region). Among the Mammals of the Sonoran region, are the Mexican deer, the American antelope, the Carolina squirrel, some hamsters, some jumping mice, the Romerolagus, the puma, some species of Canis and Vulpes, various shrews, Chiroptera and, among the Marsupials, the opossum. Among the Neotropical mammals are noticed some monkeys like spider monkey, some Bats Fillostomatidi, jaguar, ocelot, Tigrinya cat, various raccoons and martens among the Carnivores; the peccary among the ungulates; among the rodents various species similar to our porcupine; some species of Toothless including the armadillo and the anteater. The ornithological fauna includes very few species typical of the region. Reptiles are represented by Heloderma horridum, various Ophids and alligators and caimans in rivers. The Anuri amphibians include, among other things, a large frog (Rana mugiens) and the Nototrema; the Urodeles the characteristic Amblystoma mexicanum. Among the invertebrates, terrestrial molluscs and insects abound, represented by holoarctic types and neotropical species.
