What is La Niña?

La Nina is just the opposite of El Nino. When El Nino is warming of the surface water of the Pacific Ocean, La Nina is the cooling, since it is being characterized by beyond or below normal cooling effect of process of upwelling. Usually, La Nina would take place when there is a strong trade winds coming from the east to west and it would drag the surface water of the Pacific Ocean, towards the western side of the Pacific Ocean. And that trade winds somehow would cause the process of upwelling. So the deep sea cool water will be moved towards the surface of the Pacific Ocean, and that would cause a drop in the surface temperature. And well, trade winds, these are kinds of winds circulated because of the rotation of the Earth through its axis. And also, because of the differential temperature or heating of the Earth's surface.