86 THE PHYSICAL GEOGRAPHY OF THE SEA. 



nearer the equator in the winter and spring months than at any 

 other season. 



The southwest winds commence at this season to prevail as far 

 down as the lower part of California. In winter and spring, the 

 land in California is cooler than the sea air, and is quite cold 

 enough to extract moisture from it. But in summer and autumn 

 the land is the warmer, and can not condense the vapors of water 

 held by the air. So the same cause which made it rain in Ore- 

 gon now makes it rain in California. As the sun returns to the 

 north, he brings the calm belt of Cancer and the northeast trades 

 along with him ; and now, at places where, six months before, the 

 southwest winds were the prevailing winds, the northeast trades 

 are found to blow. This is the case in the latitude of California. 

 The prevailing winds, then, instead of going from a warmer to a 

 cooler climate, as before, are going the opposite way. Conse- 

 quently, they can not, if they have the moisture in them to make 

 rains of, precipitate it under such circumstances. 



131. Panama is in the region of equatorial calms. This belt 

 of cahns travels during the year, back and forth, over about 17° 

 of latitude, coming farther north in the summer, where it tarries 

 for several months, and then returns so as to reach its extreme 

 southern latitude some time in March or April. Where these 

 calms are it is always raining, and the chart shows that they hang 

 over the latitude of Panama from June to November ; consequent- 

 ly, from June to November is the rainy season at Panama. The 

 rest of the year that place is in the region of the northeast trades, 

 which, before they arrive there, have to cross the mountains of the 

 isthmus, on the cool tops of which they deposit their moisture, 

 and leave Panama rainless and pleasant until the sun returns north 

 with the belt of equatorial calms after him. They then push the 

 belt of northeast trades farther to the north, occupy a part of the 

 winter zone, and refresh that part of the earth with summer rains. 

 This belt of calms moves over more than double of its breadth, 

 and nearly the entire motion from south to north is accomplished 

 generally in two months. May and June. 



132. Take the parallel of 4° north as an illustration : during 

 these two months the entire belt of calms crosses this parallel, and 

 then leaves it in the region of the southeast trades. During these 

 two months it was pouring down rain on that parallel. After the 



