Popular Science Monthly/Volume 53/October 1898/Weather Freaks of the West Indies
| WEATHER FREAKS OF THE WEST INDIES. |
By F. L. OSWALD.
A UNITED STATES army officer, who describes the trials of garrison life in the far Southwest, remarks that the valley of the Rio Gila, though an inferno of dyspeptics, would be a paradise of weather observers, as they could stereotype their reports for a year in advance, and then go to sleep, merely leaving instructions to be waked at the approach of the one annual rain shower.
With a similar precaution for a possible lucid interval of showers, certain districts of western Oregon might enable an employee of the Signal Bureau to indulge at least the luxury of hibernation; but with every mile farther east the use of stereotypes would become more precarious, and the busiest American colleague of those Pacific sinecurists would probably be a "forecast manager," stationed on the southeast coast of Cuba.
Weather changes depend upon a variety of local conditions, modified by external influences, and on the two main islands of the West Indies the aggregate of those factors is complex indeed. A number of densely wooded mountain ranges, varying from low hill chains to Alplike sierras, alternate with arid plains and reeking jungles, and air currents from the eight principal points of the compass are apt to cause as many different modifications of humidity and temperature.
These imported meteorological tendencies have often to be taken into account to explain the curious weather freaks of special districts. The almost infallible visitations of cold waves that interrupt the summer heat of our Atlantic coast States about the beginning of July have been ascribed to the transit of iceberg chains drifting southward after the melting of their arctic moorings; but in the province of Santiago de Cuba these cooling and even chilling breezes come from the southwest, and have been traced to a reduction of temperature caused by the tremendous rainfalls in the coast forests of Honduras and Yucatan.
Straight west winds, on the other hand, often raise the mercury thirty degrees above the average of the summer season. The Gulf of Mexico has failed to neutralize the sirocco breath of the burning sand wastes flanking the valley of the Rio Grande. In the coast towns of Puerto Principe southern breezes may cool a midsummer night sufficiently to drive the natives from their house-top dormitories, and make foreigners supplement the scant bed cover of their posada with the contents of the dry-goods trunk; but the next night the northward shifting of the sea wind will illustrate the wisdom of the architect who has crowned the conveniences of the dwelling house with a domestic summer resort. The interior of the building becomes absolutely untenable, the prejudices of the night-air-dread yield to the instinct of self-preservation, and before the noon of the next day the sweltering tenants begin to suspect the influence of a volcanic catastrophe or the possible correctness of Professor Falb's hypothesis of calorific meteor clouds.
But solar agencies are, after all, sufficient to account for the grievances of the atmospheric conditions. A brisk east wind will carry samples of African summer climate, sand haze and all, two thousand miles to seaward, and it might be questioned if the gehenna of the Great Desert could have aggravated the horrors of that afternoon of June 17, 1859, when the air waves from the Mexican alkali plains roasted the pears in the orchards of Santa Barbara, California, and blistered the arms of fishermen in San Pedro Bay.
The increasing frequency of droughts in the northwest provinces seems, however, to be mainly due to local causes. In the course of the last two hundred years the sugar and tobacco planters of western Cuba have cleared some five thousand square miles of once densely wooded coast plains, and a considerable portion of that area has shared the fate of the neglected grain fields on the east shores of the Mediterranean; uniform crops have at last exhausted the fertility of the soil, and winter rains have seamed the hill slopes with arid gullies. But in summer the moisture-freighted sea winds approach the thirsty coast lands in vain. Ascending air currents, caused by the refraction of sun rays from the treeless plain, sublimate the humidity of the atmosphere into a transparent haze, or waft the clouds across the low mountain ranges and the farther foothills of the island, which here measures hardly fifty miles from shore to shore.
From the terrace lands of San Cristobal (eighty miles southwest of Havana) heavy banks of clouds may often be seen rolling up from the Caribbean Sea, and twinkle with flashes of electric fire as they approach the chain of low islands which in a former geological period seems to have bridged the strait of Los Pinos. The afternoon heat increases with every minute, and all atmospheric auspices appear to herald a thunderstorm. Far in the south the horizon is streaked with evidences of a heavy shower, and thunder peals echo along the coast cliffs; but the sky overhead is still clear, and as the clouds approach the treeless vega their shadows pale, their masses dissolve and pass the island in the form of feathery cloudlets, high sailing and wholly revoking the promise of rain.
From the summits of the central sierra those same clouds may, perhaps, be seen lowering as they continue their northward course, and lavish torrents of rain on a reef of unappreciative rocks in the Strait of Florida. Billions of gallons for the felucca skippers who fill their water barrels by means of rain sails, but not one drop for the parched plantations of the tree-destroyer.
Less easy to explain is the mania for cloud bursts which in certain years seems to seize the climate, both of eastern Cuba and northern Santo Domingo. As a rule, the rainy season begins about the middle of June and continues till late in September or that part of October when lucky Colon realized the dream of his life, and for the next ten weeks had cause to consider the climate superior to that of the Andalusian garden lands. But there are summers when the American colonists hesitate to aggravate the temperature of the national holiday with fireworks, and when heretics and true believers have to combine their prayers for showers enough to save the pineapple harvest.
In such years droughts or dryish sultry weather may continue to the end of July, but before the middle of August Nature evinces a disposition to make up for lost time, and monstrous thundershowers occur day after day, till the roar of the sierra brooks can be heard from a distance of several miles. And the land's appetite for these potations appears to grow with every indulgence. The first sensation of drowning is said to be pleasant, rather than otherwise, but that rule admits of an exception in the case of a wanderer caught in a Cuban chorasso and feeling his influenza-resisting ability yield to the persistence of the merciless shower bath till the remains of his vital vigor flicker on the verge of extinction. Yet, during the intervals of these celestial waterfalls the atmospheric condition may not appreciably differ from those of other year*; the same cool nights, the same mist-dispersing land winds and balmy mornings; warm but breezy forenoons, the cooling sea wind subsiding about 11 a. m.; then clouds and boding thunder growls. At 2 p. m. the thermometer may indicate 95° in the shade; the exact average of normal years at that time of a summer day; but again the extravasation of moisture, which, according to the rule of averages ought to be limited to a good, brisk shower, will come in the form of a deluge. After four or five weeks of such excesses the weather does begin to recover its temper, and a peculiar cool vapor, hovering about the drenched woodlands, seems to counteract the formation of waterfall clouds, the noonday hours still grow sultry, and thunder mutters its warnings on general principles; but the natives decline to stampede; experience has taught them that the wrath of Nature has been propitiated, and that the peril of atmospheric dam-breaks is over for that year.
Torrent summers occur about once in four years, and while they last the discomforts of travel in the interior of Cuba can hardly be exaggerated. The railroads of the coast plain have become bayous, and mountainward tourists need their water boots in every glen; the gnat veil of ordinary years has thickened to heavy banks of gnat clouds, and the nights are made ghastly by the serenades of renegade tomcats that have exchanged the shelter of their native ranches for the freedom of the woods, but have to wait for the cloud-dispelling moon to celebrate their declaration of independence.
The supposed rain-attracting excess of heat has, however, nothing to do with the intervention of rainy summers. In the western provinces, where rain is often sorely needed, they are rare—much rarer, at least, than in the wood-covered southeast. Their recurrence seems somewhat to depend upon the above-mentioned cold-air waves from the woodlands of Central America, cool weather in June having a tendency to postpone the beginning of the rainy season and to increase the vehemence of the eventual downpour. In other words, the early showers of Yucatan and of the West Indian Islands are apt to occur in alternate years, but there are summers when cloud bursts break out without any other premonition but the steadily increasing sultriness of the weather during the latter half of July.
Hurricanes are still harder to predict. Experience has proved that they are generally more frequent in Santo Domingo and Porto Rico than in the western Antilles, but the occasional destructiveness of their rage in Cuba is attested by numerous cadenzas, or tracts of leveled forest lands, from Santiago to Pinar del Rio, and their genesis is still rather obscure. As a rule, the equalization of extreme contrasts of temperature is attended with violent gales, and in early spring northwest storms, traversing the mainland from Hudson Bay Territory to southern Texas, may approach the threshold of the tropics nearly a hundred degrees cooler than the atmosphere brooding over the coast plains of San Salvador, where pears begin to ripen in April. And the fortnight following the vernal equinox is really a season of shipwrecking gales, in east America as well as in western Europe and the Asiatic coast lands of the North Pacific. But the tornadoes proper, the wall-breaking and tree-uprooting whirl storms of the West Indies, are more frequent in August than in April, and may even assume their most portentous forms in September, when the summer sun at last prevails against the mists of the rainy season, and the vegas are some twenty or thirty degrees warmer than the Texas prairies—a mere trifle compared with the contrasts of early spring.
Moisture would seem to play almost as important a part as heat in the generation of cyclones, and Professor von Tschudi called attention to the fact that the dry if not wholly rainless coast regions of Peru enjoy a remarkable immunity from destructive storms.
Cold winds become afflictive only on the highest plateaus of the West Indian sierras, and could be made to serve a sanitary purpose in the valles ventosos, or wind gaps of the Cuban coast range, where the eastern trade wind pours as through a funnel, all the day long, for at least eight months out of twelve. The half-wild cattle of the uplands wander miles to seek the air currents of these glens in midsummer, and can be seen standing motionless, facing due east, like orthodox Mussulmans, to enjoy the blessing of refrigeration, while the air of the grassy table-lands round about trembles under the rays of a vertical sun.
On the crest of the Sierra Maestra, at an elevation of nearly eight thousand feet above tide-water, winter winds become chilly enough to discourage permanent settlements, though herders camp there at a safe distance from the showers of the rainy season; but more grievous than any kind of air in motion are the ahogassos, or spells of stifling calms, which in early summer often continue for days together. The afternoon heat becomes insupportable on such days, at least to foreigners, who crowd the verandas of the seaport hotels, plying their fans with desperate energy, while the indolent Creoles hang in their hammocks, trying to counteract the feeling of discomfort with nicotine fumes.
