DISTRIBUTION OF RAINS. • 139 



clouds begin to form { about twelve o'clock the rain begins to 

 pour, and it continues to pour until four or five o'clock in the 

 afternoon, when the clouds break away and the evenings are 

 glorious, and during the night not a drop of rain falls. A similar 

 succession of changes occurs throughout the days of the entire 

 rainy season. How unlike the rainy days or rainy seasons of our 

 own latitude. Indeed; our rainy season is throughout the entire 

 year. It may rain here at any time, as we know. It may rain in 

 the night or in the day, and a storm may continue one day or dur- 

 ing a number of days. But in the tropics, all these phenomena 

 of nature seem to be periodical in their chai'acter. The winds 

 (constant) prevail there in one direction throughout the entire 

 year, save in the Indian Ocean, where they prevail in two direc- 

 tions — as monsoons ; but the character of the rainy days is the 

 same from day to day and from year to year. 



In the large peninsulas of southern Asia, there is one rainy and 

 one dry season. Durfng the time that the northeast monsoons 

 prevail, the eastern coast of these peninsulas are flooded with 

 rain, and the western coasts are nearly or entirely dry; while 

 during the time of the southwest monsoons, the western coasts re- 

 ceive (heir bounty of rain, and the eastern coasts are dry. In the 

 southern part of South America the rainfall is also periodical. 

 You will observe (a large map was used) that the southern part 

 of South America is in the path of the return trade winds, and 

 since these winds come to the western coast charged with mois- 

 ture, rain is precipitated during the winter months, when the land 

 is colder than the surrounding water, and hence seems to produce 

 condensation. Indeed, at the southern extremity of South Ameri- 

 ca, rain is said to fall nearly all the time. In California also the 

 rainfall has a periodical character ; and here also the rainy season 

 is during the winter months. Rain does not fall lier^ in summer, 

 for the reason that when vapor-bearing clouds, borne by the 

 southwest return trades, reach the coast, the lands are more high- 

 ly heated than the ocean, the temperature of the clouds is raised, 

 their capacity for moisture increased, and hence no jDrecipitation 

 can take place ; but during the winter months, when these warm 

 clouds come in contact with the cold summits of the mountains, 

 their moisture is precipitated and thrown down in the form of rain. 

 Thus on tlie western side of the Sierra Nevadas is an abundant 

 rainfall, while on the eastern side, between the Sierra Nevada and 

 the Rocky Mountains, the region is dry and barren, since the 



