Fig. 107—Rainfall of Morococha. [107] A shows daily rainfall during the rainy (summer) season, 1908-1909. [107] B shows monthly rainfall from July, 1905, to December, 1911, and [107] C the annual and mean rainfall for the same period.
The mean for the above six years amounts to 40 inches (1,024 mm.). This is a value considerably higher than that for Caylloma or Santa Lucia. The greater rainfall of Morococha is probably due in part to its more northerly situation. An abnormal feature of the rainfall of 1908, the rainiest year, is the large amount that fell in June. Ordinarily June and July, the coldest months, are nearly or quite rainless. The normal concurrence of highest temperatures and greatest precipitation is of course highly favorable to the plant life of these great altitudes. Full advantage can be taken of the low summer temperatures if the growing temperatures are concentrated and are accompanied by abundant rains. Since low temperatures mean physiologic dryness, whether or not rains are abundant, the dryness of the winter months has little effect in restricting the range of Alpine species.