Glaciation at elevated sites in low latitudes has the potential to play an
important role in the global radiation budget because the magnitudes of inc
oming and reflected shortwave radiation are so large. A climatic mechanism
is presented which provides a positive feedback for glaciation in the Himal
ayan mountains. A higher bare surface albedo in the Himalayas induces an at
mospheric circulation response that consists of cooling and descent over th
e Himalayas and warming and a contrasting air mass uplift to the west over
the Persian Gulf and the Arabian peninsula. Although annual mean rainfall o
ver the subcontinent south of the Himalayas decreases, the summer southwest
erly monsoon winds are stronger over the mountains in northwestern India an
d carry more moisture to higher elevations where it is precipitated as snow
. Conversely in wintertime, the northeasterly monsoon winds are weakened ov
er the Himalayas and surface wind convergence and snowfall are increased th
ere. Increased snowfall in the mountains expands the surface area of the hi
gh albedo region in both seasons, leading to a positive feedback. The peak
amplitude of this feedback is ultimately regulated by springtime melting ra
tes. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.