Equatorial zone

“ The Equatorial zone, for instance, is characterized by extreme luxuriance in growth, owing no doubt to the great heat and abundant moisture therein, and exhibits a vegetation which is peculiar to itself, and which could only thrive under the hygrometric, thermometric, telluric, and other conditions of that extensive zone. ”

“ One great physical barrier would, however, even then exist; the hot equatorial zone would divide the faunas and floras of the colder regions of the northern and southern hemispheres from any chance of intermixture. ”

“ The result is that this heated equatorial zone is constantly sending up warm air caused by the inrush of colder air, which is heavier than the air at the equator, expanded by the heat. The warm air at the equator is forced up into the higher regions of the atmosphere, and here it overflows each way, north and south, causing a current of air in the upper regions counter to that of the lower. ”

“ Excepting some portions of the equatorial zone, where the seasons recur with tolerable constancy, our notions of the climate of a place are got at by taking an average among a great many successive seasons. It is true that our own islands afford an extreme instance of variability ”

“ Taking the surface of the earth generally, the trade-winds of the southern are probably stronger than those of the northern hemisphere, and, if it were true that the south temperate and frigid zones were colder than those of the other hemisphere, it would be allowable to argue that the greater difference of temperature as compared with the equatorial zone was the cause of the greater strength of the trade-winds. ”

“ As the equatorial rains take place in the flat country when the sun passes through the zenith of the place, that is, when its declination becomes homonymous with the zone comprised between the equator and one of the tropics, the waters of the Amazon sink, while those of the Orinoco rise perceptibly. ”

“ The boundaries of the Neotropical or Tropical American region have been sufficiently indicated in the definition of the equatorial zone. A broad and most irregular band of country, in which the South and North American forms are mixed, exists in the north. ”

“ Winds depend primarily on the local distribution of heat in the air, especially on the great amount of heat constantly present in the equatorial zone, due to the sun being always nearly vertical at noon, and to its being similarly vertical at each tropic once a year, with a longer day, leading to even higher temperatures than at the equator, and producing also that continuous belt of arid lands or deserts which almost encircle the globe in the region of the tropics. ”

“ Characteristics of the Tropics.—The dominant characteristic of the great equatorial zone is the remarkable simplicity and uniformity of its climatic features. The tropics lack the proverbial uncertainty and changeableness which characterize the weather of the higher latitudes. Within the tropics, weather and climate are essentially synonymous terms. Eegular conditions, which depend upon the daily and annual march of the sun, are dominant. Irregular weather changes are wholly subordinate. ”

“ Influence of Winds on the Temperature of the Equator.—The distance from the northern to the southern tropics being considerably more than three thousand miles, and the area of the intertropical zone more than one-third the whole area of the globe, it becomes hardly possible for any currents of air to reach the equatorial belt without being previously warmed by contact with the earth or ocean, or by mixture with the heated surface-air which is found in all intertropical and subtropical lands. ”

“ Men " iu a pre-eminent sense, a region which further comprises the whole of the south torrid zone, and even extends beyond the equator us far as the Kameroon highlands. Like the vege- table species of the equatorial regions, which have gradually invaded the seaboard, attracted, so to say, by the warm marine currents carrying their seeds from shore to shore ; like the northern animals which have spread along the coast of the Indian Ocean to the southern extremity of the continent ”

“ It is known that the southeast trade-winds prevail in the Atlantic ocean, between the African and American continents, south of the equator to the tropic of Capricorn, and the northeast trade to the southward of the tropic of Cancer. It is of course generally understood, that the sun heats the equatorial regions to a higher temperature than is found anywhere else, and that the air over these regions is consequently expanded and rendered lighter than that which envelops the regions at a distance. ”

“ This surprising fact seems most improbable to those who are not acquainted with the Protectorate, but it must be remembered that temperature and climate depend on elevation as much as on geographical position. The best-known equatorial countries—such as West Africa, Brazil, and the Malay Archipelago—are comparatively low and flat. It is only rarely, as in Bolivia and East Africa, that we find the much rarer combination of equatorial position and considerable altitude. ”

“ If with the same amount of land the continents had been so grouped as to occupy a considerable portion of the equatorial oceans—such as would have been the case had Africa been turned so as to join South America, and Asia been brought to the south-east so as to take the place of part of the equatorial Pacific, then the great ocean-currents could have been but feeble or have hardly existed. ”

“ It will be plainly seen that all these points of countries lean toward the Equatorial center of motion. The islands of Oceanica, strung out on the line of the Equator, also show the effect of the Earth’s revolution.
The Island of Australia is apparently a new production in embryo of a new continent in future connection with some of the large adjacent islands, and ultimately of most of the island groups of Oceanica. The same result is likely to follow with the Greater and Lesser Antilles.
The rivers are marked evidence of centrifugal force on both continents. ”

“ The air of the equatorial belt, heated throughout the year, necessarily rises and creates an indraught from both north and south; but since the air thus flowing in has a lower rotary velocity than the earth’s surface at the Equator, it lags behind and so gives rise to northeast and southeast winds, respectively, between the two tropics and the equatorial belt. ”

“ But the large masses of land, of uneven surface, which occur between the tropics, and the consequent inequalities of temperature, check the tendency of the intertropical atmosphere to a regular course, introduce derangement in its movements, so that it is only in the great open seas that the trade-winds are experienced. Still, it has been observed that, in some countries under and near the equator, constant easterly winds are found, which are no doubt identical in their cause with those that distinguish the equatorial regions of the ocean. ”

“ Commencing at this parallel of 30°, therefore, in the North Pacific, and tracing thence the course of the north-east trade-winds, we shall find that they blow thence, and reach the region of equatorial calms near the Caroline Islands. Here they rise up; but, instead of pursuing the same course in the upper stratum of winds through the southern hemisphere, they, in consequence of the rotation of the earth (§ 207) , are made to take a south-east course. ”

“ Blowing with regular force on the surface of the sea, they cause it to move in the same direction in which they are travelling; and, this motion once acquired, the ocean stream keeps up its course far beyond where its original propelling power directly acted upon it. The ‘Great Equatorial Current’ is produced by the south-east trade, the Gulf Stream, as I’ve just explained to you, by the western or passage winds ”

“ If we here recognise the mainspring of the Gulf Stream mechanism, or rather of the whole system of oceanic circulation-for the movements observed in the Atlantic have their exact counterpart in the Pacific—we shall have no difficulty in accounting for all the motions which that mechanism exhibits. We need no longer look upon the Gulf Stream as the rebound of the equatorial current from the shores of North America. Knowing that there is an underflow towards the equator, we see that there must be a surface-flow towards the Poles. ”

“ We are now at an elevation of about four thousand feet, and steadily nearing the equator, although the climate gives little sign of it. It is a popular mistake that the nearer one goes to the equator the temperature must necessarily increase. Were this so, Africa, which is the most tropical continent in the world, would also be the hottest; while the torrid zone, which occupies so large a portion of it, would be almost insupportable to the European. On the contrary, the nearer one goes to the equator in Africa it becomes the cooler. ”

“ So both the Gulf Stream and the Black Stream are merely parts of a big oceanic whirlpool. Each ocean on Earth has its own system of circulation; and that system is part of a world-wide system. The waters are in perpetual and complicated motion. Streams pour incessantly hither and thither, to north and south, to east and west.
Two vast streams, known as the Equatorial Currents, nominally pour round the world, but really are best seen in the open Pacific, where for long distances no land meddles with their career. They flow steadily westward, one to the north and one to the south of the equator. ”

“ Professor Suess, again, believing that in equatorial regions the sea is, on the whole, gaining on the land, while in other latitudes the reverse would appear to be the case, points out this is in harmony with his view of a periodical flux and reflux of the ocean between the equator and the poles. He thinks we have no evidence of any vertical elevation affecting wide areas, and that the only movements of elevation that take place are those by which mountains are upheaved. ”

“ The theory that the difference of density caused by the difference of temperature between the polar seas and the equatorial oceans made under-currents to flow from the polar latitudes, and meet in the equatorial seas, can only be carried on in the Atlantic Ocean, and in a comparatively less perfect way in the Pacific Ocean, and not at all in the Indian Ocean. ”

“ See the immense equatorial flow to the east of Australia, and which I have called the Polynesian Drift. It is bound for the icy barriers of that unknown sea, there to temper climates, grow cool, and return again, refreshing man and beast by the way, either as the Humboldt current, or the ice-bearing current which enters the Atlantic around Cape Horn, and changes into warm again as it enters the Gulf of Guinea. It was owing to this great southern flow from the coral regions that Captain Ross was enabled to penetrate so much farther south than Captain Wilkes on his voyage to the Antarctic. ”

“ It may be considered as beginning on the west coast of Africa, within the region of the trade winds. These cause a westward flow, known as the equatorial current. On reaching the coast of Brazil, the greater portion of this current bends northward, carrying with it the waters of the Amazon and Orinoco, and passes through the Caribbean Sea into the Gulf of Mexico. ”

“ Rising up at the equator, it did not leave all its moisture with the cloud-ring, but, retaining a part, conveyed it through the cloud region, above the north-east trades, to this calm belt, where there was a descent and a crossing. The fact that these dry places are all within or on the equatorial side of this calm belt, while countries abounding with rains and well watered with running streams are to be found all along its polar side, is clearly indicative of a crossing. Upon no other supposition can we account for the barrenness on one side, the fertility on the other. ”

“ The shores of the Gulf of Guayaquil and part of the Ecuadorian coast are vividly green from the dense mangrove thickets and other vegetation, but as soon as the mist zone of the Equator is left behind the coastal zone becomes stark and unfruitful, beaten by tearing surges between the few havens. ”

“ The equatorial regions are then, as regards their past and present life history, a more ancient world than that represented by the temperate zones, a world in which the laws which have governed the progressive development of life have operated with comparatively little check for countless ages, and have resulted in those infinitely varied and beautiful forms—those wonderful eccentricities of structure, of function, and of instinct—that rich variety of colour, and that nicely balanced harmony of relations—which delight and astonish us in the animal productions of all tropical countries. ”

“ By reason of this variation in temperature and soil, all the products of the torrid and temperate zones can be cultivated.
The average person has a habit of associating tropical lands with the idea of intense and disagreeable heat. This person does not stop to think that the conditions are often much different from what they seem on the map. Even at the equator, which one would naturally think almost uninhabitable, the upland sections are just as well adapted for the abode of white people as the temperate zone. ”

“ They have their birth where the moist, still air above the ocean in the region of the doldrums at the season when the equatorial belt of calms is farthest north, becomes highly heated and rises on account of the pressing in of cooler and heavier air from adjacent regions. The ascending column is at first carried 211 slowly westward, in obedience to the general flow of the atmosphere in the intertropical belt, and at the same time the currents coming in from opposite directions give the ascending air a rotary motion. ”