4 BULLETIN 211, U. S. DEPARTMENT OF AGRICULTURE. 



and June each year if there has been a normal rainfall the previous 

 summer. But it is true of practically all of the State that May and 

 June are the driest months of the year, and summer arrives without 

 any heralding by spring. It has been said that there are but two 

 seasons in the southern valleys, summer and late fall, and the longer 

 of these is summer. The summer rains usually occur as rather violent 

 local showers of short duration. The water falls from clouds that are 

 high above the earth, and the air next the ground may be relatively 

 dry; in fact, it is not infrequent to see small, high clouds that are evi- 

 dently producing some rain, but the water evaporates at a lower level 

 and never reaches the ground. Drizzling rains from low-hung, drift- 

 ing clouds that roll along only a few hundred feet above the earth are 

 only occasional anywhere except upon the cloud-capped peaks of the 

 high mountains ; and heavy general storms moving steadily over large 

 areas are very rare. 



A study of the United States Weather Bureau reports indicates 

 that there are two factors fundamental in nature which determine 

 in a general way what the average precipitation of any point in 

 the State shall be. The first of these is the well-known relation 

 between precipitation and altitude, depending upon the effect of 

 forcing currents of moisture-laden warm air to higher atmospheric 

 levels through the upward deflection of such currents by the moun- 

 tains. It thus happens that, other things being equal, the precipita- 

 tion increases with altitudinal increase, though not always in a direct 

 ratio. 



The average precipitation of any station in the State also seems 

 to be in some way dependent upon its distance from the southeast 

 corner. If. localities having the same altitude be considered, it 

 appears that those in the southeastern corner have the greatest 

 average rainfall, and that this rainfall gradually diminishes as one 

 goes west and north. This fact would seem to suggest that the 

 source of the moisture lies to the southeast, possibly the Gulf of 

 Mexico. Local factors enter into the case, sometimes decreasing, 

 sometimes augmenting the amount of precipitation for a particular 

 location. Some of the extreme records for the State follow and will 

 give an idea of the limits of variation. A normal rainfall chart for 

 New Mexico has been published by the State immigration bureau. 



The maximum precipitation in the State recorded for any single 

 calendar year is for Elk, 39.1 inches, in 1905. There is possibly 

 some inaccuracy in this record, or the station is subjected to local 

 conditions which tend to increase the normal expectancy for this 

 altitude, 7,400 feet. Cloudcroft (8,650 feet) received 32.32 inches 

 in 1905; Chama (7,851 feet) received 32.83 inches in 1891; and the 

 highest record for Windsor (8,200 feet) is 27.92 inches in 1907. The 

 lowest records occur in the lower valleys. San Marcial (4,439 feet) 



