In the Mexican Republic there are zones with pluvial precipitation of 4,000 mms., such as 
Tapachula in Chiapas and Teapa in Tabasco; in other zones, the rainfall is very low, such 
as in the South of the Penninsula of Baja California. On the map annexed you can 
examine the isoyet (isoyetal lines) which determines the pluviometric regions of the coun- 
try and which confirms the ideas that are briefly stated. Fig. 6. 
Talking about the atmosphere we can say that thick layers of smoke (1) covers great 
extentions of land specially during the months of March and April. 
ESTADOS UNIDOS DE AMERICA 
DE MEXICO 
e 
Isoyet ort 
CARTA ISOYETAS DE LA 
REPUBLI MEXICANA 
Precipitacion medio onual en | 
milimetros periodo 1921-1951 m e 
(odaptado de! Atlas Geografico 
General de Mexico de Jorge L. 
Tomoyo publicado en 1962 ) 
SIGNOS CONVENCIONALES 
Hasta 200 milimetros 
de 200 o 300 milimetros 
de 300 9 500 milimetros 
de 500 a1000 milimetres 
mos de  |OOOmilimetres N | 
REPUBLICA MEXICAN 
108° | | | 
  
Fig.6 
  
(1) The fires constitute a favorite agricultural practice, used by certain types of farmers and 
consist in eliminating the remains of previous crops by means of incinerating the 
residue.