23 



" Between the points from whicli these opposing surface belts of wind begin 

 to rise, there is a belt of rains also encircling the earth, and about five hun- 

 dred miles wide. It is called the rainy belt, and from it pour down those tor- 

 rents of rain which fall on Central America. 



"As these dry surface trade- winds pass over the land and the ocean, they ab- 

 sorb immense quantities of moisture, and their capacity to hold it is increased 

 by the great heat imparted to them from the rays of the vertical sun. After 

 they have risen, and become the upper or counter trade, the north one passes, 

 at first, in a northern direction ; but on account of the diurnal rotation of the 

 earth, it is gradually turned to the east, forming the southwest wind, so general 

 during summer in the Atlantic States. As it passes northwards into colder 

 atmosphere it loses its heat ; the moisture, in consequence, condenses, and at 

 about fifteen degrees north of the equator portions of the wind and moisture 

 descend to the earth. Other portions having received the latent heat liberated 

 from the moisture that has descended as rain, continue northwards even to the 

 north pole. The portions of the earth receiving these rains are called the extra 

 tropical rainy regions. 



" This central rainy belt and these two belts of dry trade-winds follow the 

 sun in its passage north of the equator to the tropic of Cancer, which is nearly to 

 the twenty-fourth degree of latitude. As the northern edge of the dry trade- 

 winds reaches fifteen degrees north of the latitude of the sun, when the latter is 

 at the tropic of Cancer, this northern edge reaches to about the thirty-ninth de- 

 gree of latitude, being within three degrees of the northern boundary line of 

 California. But before the sun reaches the tropic of Cancer, and after it begins 

 to recede from it, northern California receives the rains that fall beyond the dry 

 trade-winds. Thus this part of the State receives m'ore rain than the southern 

 portion, which is longer covered by the trade-winds." 



The northwest wind, therefore, is dry, because in passing from the equator to 

 the pole it has parted with all the moisture it had absorbed, Avhen rising into 

 the upper regions of the atmosphere at the equator. Hence, as our correspondent 

 says, " in the dry season the wind invariably blows from the northwest." 

 During last winter this wind continued blowing from the same direction, instead 

 of from the southeast, as it usually does in winter, Avhich is the wet season. 

 Why it did so we cannot tell, nor do we suppose that meterology can furnish a 

 satisfactory explanation. 



But we have just seen that the wind which brings rain is the southwest wind. 

 Why, then, has it been so dry this summer in California? Simply because the 

 dry trade-wind belt had extended over most of California, and it must have been 

 these dry winds turned from their usual course, by the cause which kept the 

 northwest wind over California during winter. The true moist southwest wind 

 descends to the earth beyond the dry trade-wind belt. Hence, although they 

 came over the ocean, they had not yet absorbed the evaporations of the ocean. 

 How far they passed over the ocean, and whether they came from the southern 

 hemisphere or the northern, cannot be determined ; but the latter, in all proba- 

 bility. 



But why are the winds of the wet season in California from the southeast 1 

 Why are they not the southwest winds, as in this part of the Union ? 



East winds are mere surface winds, and caused by an approaching fall of 

 rain and snow, or condensation. We have them here in winter. But the rain 

 comes from the higher strata of clouds, which are moving from the southwest to 

 northwest. Thus, in some marked rains of the past winter, during which, and 

 for twenty-foiir hours before their fall, the wind blew constantly from the north- 

 east the newspapers show that they commenced falling from four to six hours 

 at Washington, before they commenced at Boston. Tliey were traced at Balti- 

 more, Philadelphia, New York, and Boston, moving directly against the north- 

 east wind. In California, the Nevada range of mountains run, from the southeast 



