Look carefully at the relevant diagram first!

During the northern hemisphere [?], the overhead sun, the ITCZ and the sub-tropical jet [?] all move southwards. At the same time, central [?] experiences intense cooling which allows a large [?] pressure system to develop. Airstreams which move outwards from this high pressure area will be [?] because their source area is semi-desert.

They will become even drier as they cross the [?] and adiabatically warmer as they descend to the Indo-Gangetic [?]. Mumbai receives less than 100mm of rain during these 8 months.

The monsoon, which in reality is much more complex than this model described here, affects one [?] of the world's population. Unfortunately, monsoon rainfall, especially in the Indian sub-continent, is unreliable. If the rains fail, then [?] and famine will ensue. 1987 was the ninth year in a decade when the monsoon failed to arrive in north-west India. If, conversely there is excessive rainfall then large areas of land experience extreme [?] such as Bangladesh (1998, 2002 and in many other years).