Orographic Barrier of the Great Himalayas

The entire geographical literature, starting with school textbooks, presents the Himalayas as a classical model of an impermeable orographic barrier, halting the masses of monsoon air and causing aridity of the Tibetan landscapes. Despite of that, however, the author, during his trips to Western and, particularly, to Central Tibet, organised exactly during the summer monsoon, always found the southern regions of these provinces flooded to a large extent with water. It is also puzzling that catastrophic floods occurring in China (connected with the high water in rivers originating in Tibet) are correlated in time with the period of the summer monsoon in the Himalayas.