In general, monsoons work on a temperature gradient – the difference in temperature between a warming land (with lower atmospheric pressure) and a relatively cooler ocean (with higher pressure). Winds blow from high pressure to low pressure areas, driving moisture-laden winds from ocean to land. When the land warms up faster – as it did without its usual aerosol shade – the monsoon rains are stronger, and that's what researchers observed when the aerosol layer thinned.
