Climate öf Mexico. 149 
usually in June and last until-November, are so abundant and fall so regularly, 
especially in the afternoon, that they refresh the atmosphere. So decided is 
the effect of the rains on the atmosphere that the seasons are divided into 
two only, viz., the dry and the rainy season, which are independent of the 
elevation upon which the classification into three superimposed zones depends. 
These may be conveniently tabulated as follows: 
Hot Zone... . (Tierra Caliente) . o to 3,000 ft. 77°—82°F. (25°—27.8° C.) 
Temperate Zone (Tierra Templada) 3,000 to 5,000 ft. 62°—70° F. (16.7°—21.1° C.) 
Cold Zone ..... (Tierra Fria) .... 7,000 to 10,000 ft. 58°—-64° F. (14.4°—17.8° C.) 
Boreal Zone... ( » ) » . . 10,000 to 18,000 ft. Abi 
The mean temperature in the hot regions varies from 77: 20.80 8; 
(25°—27.8°C.), and often rises to 100° F. (37.8° C.), and in some coast loca- 
lities t0 105° F. (40.5° C.). Yet even here the atmosphere is constantly refreshed 
by the night breezes, and in summer by the rains which prevail from June 
to November and fall regularly and at fixed intervals from about one to three 
hours daily. 
The temperate zone has a mean temperature of from 62° to 70° F. 
(16.7°—21.1° C.), the variation during the season being not more than 4° to 
5°F. and it may, therefore, be called the region of eternal spring. It is 
somewhat comparable to that of Mediterranean lands. As in Algeria and 
Italy, the orange, fig and olive thrive amid wheat and maize fields. The tierra 
templada comprises all the higher mountain terraces and parts of the plateau 
itself. The Sierras rise high enough to condense some of the moisture derived 
from the neighboring seas and this condensed moisture falls as rain during 
the invierno, that is, the wet summer months. The dry season verano, 
later follows. 
Between 7,000 feet above the level of the sea and En gi ar ei 
cold region having a main temperature of from 58° to 64° F. (14.4°—17.8° C.). 
Here the rainfall is five times less than in the temperate zone. The changes 
of temperature are but small from one end of the year to the other, although 
the diurnal changes between sunrise and sunset are often considerable. bi 
higher mountains ‚ Orizaba, Popocatepetl, Ixtaceihuatl are covered wit 
snow and the conditions on these peaks above the limit of vegetation are 
More extreme and arctic. 
Tables. The following tables will present th 
Mexico as they have been reported from a nu 
Parts of the Republic. See pag. 150-151. ’ 
Climate of ie Caty Fe By way of specifically nn. n 
Climate of Mexico, that of the City of Mexico, 25 deduced from da er am: 
by Mariano Barcena‘), will be given as a sample. The mean ee = 
Perature varies from 53.6° F. (12° C.) in December to 64.4° F. ( 
m . 
e meteorologic conditions in 
mber of stations in varıous 
1 i 1 held at Chicago, August 21-24, 
en ET TER ment Agriculture. Washington 1896. 
!) Re 
1893. Bulletin II, Part 3. Weather Bureau United States Depart 
