“…It is well known that there are large spatial and temporal variations in atmospheric water vapor. Padilla, Leyva, and Mosino (1993) made psychrometric measurements for study of atmospheric humidity behavior at two places in Mexico, one in the Chaoultepec Heights, in the western zone of Mexico City at 2300 m above sea level, and another in Rancho Viejo, a mountainous wooded area at 2700 m above sea level. The distance between these places is approximately 68 km.…”