FEBRUARY
Constant cloud changes, frequent afternoon or evening rains. “Tempest,” generally 4 P.M. and later, 16 times.
MARCH
Twice clear morning skies, once starry night. Scorching sun and stifling heat on one occasion. “Tempest,” generally in late afternoon and accompanied by hail, 19 times. Observed 3 or 4 times a strong, “land breeze” (terral) of short duration (15-20 mins.) and at midnight.
Morococha
Morococha, in the Department of Ancachs, Peru, lies in 76° 11′ west longitude and 11° 45′ south latitude and immediately east of the crest line of the Maritime Cordillera. It is 14,300 feet above sea level, and is surrounded by mountains that extend from 1,000 to 3,000 feet higher. The weather records are of special interest in comparison with those of Santa Lucia. Topographically the situations of the two stations are closely similar hence we may look for climatic differences dependent on the latitudinal difference. This is shown in the heavier rainfall of Morococha, 4° nearer the equatorial climatic zone. (For location see Fig. 66.)
The meteorological data for 1908-09 were obtained from records kept by the Morococha Mining Company for use in a projected hydro-electric installation. Other data covering the years 1906-11 have appeared in the bulletins of the Sociedad Geográfica de Lima. These are not complete but they have supplied rainfall data for the years 1910-11;[36] those for 1906 and 1907 have been obtained from the Boletín de Minas.[37]
Temperature
The most striking facts expressed by the various temperature curves are the shortness of the true winter season—its restriction to June and July—and its abrupt beginning and end. This is well known to anyone who has lived from April to October or November at high elevations in the Central Andes. Winter comes on suddenly and with surprising regularity from year to year during the last few days of May and early June. In the last week of July or the first week of August the temperatures make an equally sudden rise. During 1908 and 1909 the mean temperature reached the freezing point but once each year—July 24 and July 12 respectively. The absolute minimum for the two years was -22° C. July of 1908 and June of 1909 are also the months of smallest diurnal variability, showing that the winter temperatures are maintained with great regularity. Like all tropical high-level stations, Morococha exhibits winter maxima that are very high as compared with the winter maxima of the temperate zone. In both June and July of 1908 and 1909 the maximum was maintained for about a week above 55° F. (12.8° C.), and in 1909 above 60° F. (15.6° C.), the mean maximum for the year being only 4.7° F. higher. For equal periods, however, the maxima fell to levels about 10° F. below those for the period from December to May, 1908.
It is noteworthy that the lowest maximum for 1909 was in October, 44° F. (6.7° C.); and that other low maxima but little above those of June and July occur in almost all the other months of the year. While 1909 was in this respect an exceptional year, it nevertheless illustrates a fact that may occur in any month of any year. Its occurrence is generally associated with cloudiness. One of the best examples of this is found in the January maximum curve for 1909, where in a few days the maxima fell 12° F. Cloud records are absent, hence a direct comparison cannot be made, but a comparison of the maximum temperature curve with the graphic representation of mean monthly rainfall, will emphasize this relation of temperature and cloudiness. February was the wettest month of both 1908 and 1909. In sympathy with this is the large and sharp drop from the January level of the maxima—the highest for the year—to the February level. The mean temperatures are affected to a less degree because the cloudiness retards night radiation of heat, thus elevating the maxima. Thus in 1908 the lowest minimum for both January and February was 28.4° F. (-2° C.). For 1909 the minima for January and February were 27.5° F. (-2.5° C.) and 29.3° F. (-1.5° C.) respectively.