Читать книгу The Amphibians and Reptiles of Michoacán, México - William Edward Duellman - Страница 8
Climate
ОглавлениеThe climates in Michoacán vary from tropical in the lowlands to cool temperate at high elevations in the Sierra de Coalcomán and Cordillera Volcánica. The highest temperatures are known in the Balsas-Tepalcatepec Basin, where at Churumuco the mean annual temperature is 29.3° C. and the range of monthly means is 3.5° C. (Contreras, 1942). Frosts occur sporadically on the Mexican Plateau, and in the winter snow falls on the highest mountains.
Precipitation varies geographically and seasonally. Most of the rain falls between June and October. In the Balsas-Tepalcatepec Basin rainfall in the rest of the year is negligible. The annual average rainfall at Coahuayana on the Pacific Coastal Plain is 871 mm. (Guzmán-Rivas, 1957:52). In the Balsas-Tepalcatepec Basin rainfall seldom exceeds 800 mm. per year. In the mountains precipitation is heavier and somewhat more evenly distributed throughout the year, but still definitely cyclic. For example, Uruapan (elevation, 1500 meters) receives an average annual rainfall of 1674 mm. (Contreras, 1942). The prevailing winds are from the Pacific Ocean. The southern (windward) slopes of the Sierra de Coalcomán probably receive more rain than any other part of the state. The Balsas-Tepalcatepec Basin lies in a rain shadow of the Sierra de Coalcomán, and the Mexican Plateau lies in a somewhat less drastic rain shadow of the Cordillera Volcánica; these are the driest regions in the state.