Nubes fragantes con que el ciclo llueve."
One of the peculiarities of this climate, as well as that of the coast of Peru from Arica to Cape Blanco, being a distance of about 16 degrees of latitude, is, that it can scarcely ever be said to rain. Several theories have been advanced to account for this anomaly of nature. The following facts and explanations will, perhaps, tend to unravel the difficulty.
In April or May the mists, called garuas, begin, and continue with little interruption till November, which period is usually termed the winter solstice. The gentle winds that blow in the morning from the westward, and in the afternoon from the southward, are those which fill the atmosphere with aqueous vapours, forming a very dense cloud or mist; and owing to the obliquity of the rays of the sun during this season the evaporation is not sufficiently rarified or attenuated to enable it to rise above the summits of the adjacent mountains; so that it is limited to the range of flat country lying between the mountains and the sea, which inclines towards the north west. Thus the vapours brought by the general winds are collected over this range of coast, and from the cause above-mentioned cannot pass the tops of the mountains, but remain stationary until the sun returns to the south, when they are elevated by his vertical heat, and pass over the mountains into the interior, where they become condensed, and fall in copious rains. That rain is not formed on the coast from these mists is attributable, first, to a want of contrary winds to agitate and unite the particles, and, secondly, to their proximity to the earth, which they reach in their descent, before a sufficient number of them can coalesce, and form themselves into drops.
The figure of the coast also contributes to the free access of the water that has been cooled at the south pole, on its return to the equatorial regions. From Cape Pilares to latitude 18° the direction of the coast is nearly N. and S.; and from 18° to 5° it runs out to the westward: thus the cold water dashes on the shores, and produces in the atmosphere a coolness that is not experienced in other parts, where the coasts are filled with projecting capes and deep bays; because the current, striking against those, sweeps from the coast, and the water in these becomes heated by the sun, and is deprived by the capes of the current of cold water, excepting what is necessary to maintain the equilibrium, which is diminished by absorption in the bays. The heat increases with astonishing rapidity from latitude 1° south to 10° north; the Gulph of Choco being deprived of the ingress of cooled water from the south by the Cape San Francisco, and from the north by Cape Blanco. The eastern shores of the south Continent of America are much warmer than the western, owing to the great number of capes and bays. The atmosphere does not enjoy the cooling breezes from the pole, which are diverted from a direct course in the same manner as the currents of water, nor the refrigerated winds from the Cordillera.
The southern hemisphere is altogether much cooler than the northern: perhaps in the same ratio that the surface land of the northern hemisphere exceeds that of the southern.
During the months of February and March it sometimes happens that large straggling drops of rain fall about five o'clock in the afternoon. This admits of an easy elucidation. The exhalations from the sea being elevated by the heat of a vertical sun, and impelled by the gentle winds during the day towards the interior and mountainous parts of the country, are sometimes arrested in their progress by a current of air from the eastward, which, having been cooled on its passage over the snow-topped Andes, is colder than the air from the westward; and wherever these currents meet the aqueous particles are condensed, and uniting become too heavy to continue in the upper region of the atmosphere, when they begin to fall, and in their descent combine with those that fill the lower regions, and hence some large drops are formed.
The following table of the weather will perhaps furnish a better idea of the climate of Lima than any verbal description:—
| 1805 | 1810 | |||||||
| _______________/\________________ | _________/\_________ | |||||||
| / | \ | / | \ | |||||
| Sun. | Cloudy. | Variable. | Sun. | Cloudy. | Variable. | |||
| Jan. | 5 days | 10 days | 16 days | 6 days | 11 days | 13 days. | ||
| Feb. | 8 | 5 | 15 | 7 | 4 | 17 | ||
| March | 12 | 2 | 17 | 13 | 2 | 16 | ||
| April | 7 | 9 | 14 | 6 | 10 | 14 | ||
| May | .. | 17 | 14 | 1 | 15 | 15 | ||
| June | .. | 21 | 9 | .. | 24 | 6 | ||
| July | .. | 28 | 3 | .. | 31 | .. | ||
| August | .. | 27 | 4 | .. | 30 | 1 | ||
| Sept. | 3 | 20 | 7 | 2 | 21 | 7 | ||
| October | 2 | 21 | 8 | 2 | 19 | 10 | ||
| Nov. | 4 | 16 | 10 | 5 | 15 | 10 | ||
| Dec. | 4 | 18 | 19 | 4 | 7 | 20 | ||
| — | — | — | — | — | — | |||
| During the year | 45 | 184 | 136 | 46 | 189 | 129 | ||
| == | === | === | == | === | === | |||
Sun indicates those days in which the sun was never clouded; Cloudy, those in which the sun was not visible; and Variable, those in which the sun was generally clouded in the morning but afterwards became visible.
From the foregoing explanations it must naturally be inferred, that the dry season in the interior occurs at the time that the mists or fogs predominate on the coast, and vice versa: this is what really takes place. The rivers on the coast are nearly dry during the misty weather, but during the summer heat they often become impassable, owing to their increase of water from the melting of the snow on the mountains and the fall of rain in the interior. The chimbadores, or badeadores, men who ford the larger rivers with goods and travellers, know from experience and minute observation, according to the hour at which the increase begins, at what place the rain has fallen.