HOUSTON (CW39) – Weaker trade winds are correlated with a La Nina and a hyperactive hurricane season. Weaker trade winds mean less wind shear over the Atlantic and Caribbean to break apart storms. We saw this occur in the historically active 2020 Hurricane Season, La Nina conditions were in place, trade winds weakened, and 30 named storms were able to develop.
The trade winds form between 30 degrees north and 30 degrees south of the equator. The are named this because of their use in helping sailors get from Europe to the Americas. The spin of the earth causes a phenomenon called the Coriolis effect. This sends winds slanting southwesterly in the northern hemisphere and northwesterly in the southern hemisphere. This aids in the formation of a “belt” of prevailing winds from east to west.
Weather history! Gaspard Gustave de Coriolis, a French scientist (1792-1843), is best known for his work on studying Coriolis force! He proved that the laws of motion could be applied to a rotation frame of reference, such as Earth!
There is a smaller that wraps around the globe, about 5 degrees north and south of the equator where a different type of phenomena takes place. This is where the northeasterly and southeasterly trade winds meet. We call this the inter tropical convergence zone, or the ITCZ. You can normally see the ITCZ on visible satellite due to the rigorous thunderstorm activity triggered with it. Sailors call this are the doldrums because as the winds collide from the north and south, they practically come to a halt. Calmer winds added with intense solar heating allow for the air to become very buoyant, the hot and humid air rises, creating a band of convection. This is also the reason we see environments like rainforests develop!