6 INSTITUTE OF SOCIAL ANTHROPOLOGY—PUBLICATION NO. 7 
temperatures are high over the entire Tarascan 
area, but less so in the higher Sierra. The 
warmest months are April and May, the period 
immediately before the rainy summer (May 
average temperatures: Zacapu, 19.1° C.; Uruapan, 
22.4°; Zamora, 23.2°; Cuitzeo, 23.2°; Pdtzcuaro, 
19.9°). 
Precipitation in the area, as in most parts of 
Mexico, is seasonal, 80 percent of the annual 
total falling mainly as convectional thunder- 
showers in June, July, August, and September. 
In the Sierra the summer rains often continue as 
drizzles for a period of 3 to 4 days, suggesting 
local cyclonic origin. Occasionally during the 
months of December and January light winter 
rains, called cabafiuelas, or janingerkua, occur. 
These rains prevail over most of western Mexico 
when cyclonic disturbances over the Pacific reach 
inland, a condition which occurs every 3 or 4 
years.'° Such precipitation often falls as snow 
on the higher volcanoes in the Sierra, such as 
Tancitaro, Patamban, and Quinseo. Freak snow 
storms have been recorded in historical times; in 
September 1887 several inches of snow fell in the 
vicinity of Charapan and San Felipe, caving roofs 
and destroying the maize crop.!! Another curious 
meteorological phenomenon of the Sierra is the 
prevalence of radiation fog in the low basins from 
late summer to early winter. Forming in the 
early morning hours (after 1 a. m.), the fog evap- 
orates by noon. Its presence lowers average 
daily temperatures and prevents rapid evapora- 
tion of surface moisture.” 
Annual precipitation in the area north and east 
of the Sierra averages from 750 to 850 mm. A 
greater amount is recorded around Lake Patz- 
cuaro (town of Patzcuaro, 1,109 mm.), and even 
more probably falls in the Sierra, where no records 
exist. The greatest precipitation in Tarasca is 
recorded along the southern (windward) side of 
the Sierra in the upper escarpment zone. (Aver- 
age annual totals for Uruapan, 1,683 mm.; Ario 
de Rosales, 1,225 mm.; Tacdimbaro, 1,240 mm.) 
‘0 In northwestern Mexico, particularly in Sonora and the Sierra Madre 
Occidental, the winter cyclonic storms are called equipatas. Although they 
are part of the same frontal system, the eqguipatas occur more frequently 
than the cabaviuelas since northwestern Mexico is nearer the North Pacifie 
center of frontogenesis. 
'' Lumholtz (1902, vol. 2, p. 365) states that water has been known to freeze 
in Cherfn and Zacapu on June 10. 
The Sierra fogs are often mentioned by colonial chroniclers. One, 
describing the Charapan area in 1789: ‘ . . . continwalmente se ve el terreno 
cuebierto de neblas, que evaporen y eralala humedad de latierra’’ (AGN Historia, 
vol. 73, f. 219). 
Climatic areas and associated vegetation.— 
Sufficient statistical data are not available to 
construct accurately a map showing climatic 
types in the Tarascan area. Using (1) the avail- 
able statistics from the few existing stations, (2) 
vegetation boundaries taken from field observa- 
tions and aerial photographs, and (3) elevations 
from topographic maps compiled from aerial 
photography, an attempt has been made to locate 
climatic areas based on the Koéppen system 
(map 4). 
The Sierra.—The Cwb and Cwe climatic types 
of Képpen"™ correspond to the tierra fria of the 
Tarascans—the Sierra, its eastern extension (in- 
cluding the Sierra de Ozumatlan), and the south- 
eastern part of the northern plateau area. A 
mixed oak-pine forest forms the dominant vegeta- 
tion of the Sierra and its eastern extension, and 
corresponds to the higher and colder phase of the 
Cwhb climatic zone. (Cf. maps 4 and 5.) Pinus 
leiophylla (pino chino) and P. michoacana var. 
cornuta (pino lacio) are the principal pines 
(p‘ukiri) of the Sierra (Martinez, 1945). (Pl. 1.) 
The former species is the main turpentine pro- 
ducer, while the latter, a straight, tall tree, 
affords the best lumber. Minor species of pines 
found in the Sierra include P. teocote, P. pseudos- 
trobus, and in the upper escarpment zone, the 
subtropical pine P. oocarpa. Even at high 
altitudes the pines rarely form solid stands, but 
are mixed with numerous species of oak, the latter 
dominent at lower altitudes, the former at higher 
elevations. Some 30 species of oak (urikua, 
tuktis, Sariri), both deciduous and_ persistent, 
occur in the Sierra and adjacent areas. Among 
the more common are Quercus fulva, Q. acuminata, 
Q. circinata, Q. laxa, Q. crassipes, and Q. pandurata 
(Trelease, 1924). Often mixed with pine and 
oak are madrofio (pandnksa; Arbutus sp.); various 
laurels (Lauraceae); many hydrophytes in bar- 
ranca bottoms, such as jaboncillo (saépu), palo 
blanco (udrpit-uku; Alnus sp.), palo colorado 
(éaraépit-uku). 
On lower slopes one often sees the Mexican 
“crab apple” (actually a hawthorne) or tejocote 
(kaais; Crataegus mexicana) and the “cherry” or 
capulin (Séngua; Prunus capuli), both of which 
13 Mathematical values of Képpen symbols: C, temperature of coldest 
month between —3° and 18° C.; w, dry winter, rainy summer; b, tempera- 
ture of warmest month less than 22° C.; c, temperature of coldest month 
above —38° C., and mean temperature of less than 4 months out of the year 
is more than 10° C. 
a 
