The SCS climate is part of the East Asian monsoon system
Winter (NE-Monsoon):
The cold air mass of high atmospheric pressure in the
Asian Continent spreads to the seas. It forms the northeast
monsoon going across the South China Sea, and through
the equator, it becomes the northwest monsoon in the
Southern Hemisphere.
Summer (SW-Monsoon):
the southeast trade wind in the South Hemisphere (in
winter) goes across the equator to become moist
southwest monsoon through the