a seasonal prevailing wind. Two types:

Summer monsoon: intense heating of a continental mass in summer months due to the arrival of the heat equator causes convectional uplift over the continent and hence low pressure. This draws warm moist air from relatively higher pressure maritime areas bringing high levels of rainfall and humidity.

Winter monsoon: reverse of the summer system. The heat equator is now over the maritime area and draws cool, dry air from the continental mass which means cool, dry winter months for the monsoon region.