qThe 23,000-year cycle of orbital procession increases
(decreases) summer insolation and at the same time decreases
(increases) winter insolation at low and middle latitudes.
qDepartures from the modern seasonal cycle of solar
radiation have driven stronger monsoon circulation in the past.
qGreater summer radiation intensified the wet summer
monsoon.
qDecreased winter insolation intensified the dry winter
monsoon.