Over the Equator, large hot air masses rise into the upper layers of the atmosphere. Pursuing a natural convection effect, these will seek to migrate towards the colder temperatures of the Earth's Poles. Due to its rotation and a resulting Coriolis force, these air masses are deviated clockwise in the Northern Hemisphere. This happens at around 30° of latitude over the Atlantic Ocean. When sinking down, they create a high pressure area (called Anticyclone) generally centered on the Azores Islands.
These winds originating from the Equator are largely driven by temperature differences on a planetary level. As this translates into atmospheric pressure variations, they can therefore be considered as global winds.
Unlike local winds that are influenced by the Earth's topography, the "trade winds" as they are referred to, result instead from the combined influences of the rotation of the Earth (Coriolis forces) and its latitudinal temperature differences.
The latter is relevant to the solar radiation on a spherical surface which -due to its incidence angle- cannot be as intense on its center (Earth's Equator) versus its Poles. As the hot air masses generated over the Equator are deviated to the right by the rotation of the Earth, this results into a perpetual clockwise circular air movement over the North Atlantic.
It may be relevant to mention that these fundamentals cannot change, regardless of any climate change considerations, so long that the Earth is round and rotates while exposed to direct solar radiation.
The circular movements of the trade winds over the Atlantic shape oceanic surface currents by wind stress in the exact same pathways. Geological evidence provided by the existence of the world’s largest sedimentary phosphate deposits (72 % of World reserves*) trapped at the bottom of Morocco’s Atlas Mountains, confirm that trade winds have been active for millions of years.
Indeed, high marine biological productivity associated with upwelling ocean currents along continental margins brought phosphorus-rich cold waters from deeper ocean levels nearer to the surface. Compounded by the merging of warmer Indian (and Pacific) oceans waters coming from the East, this nourished and stimulated the growth of an exceptionally rich biotope. Pushed towards a shallow area located at the bottom of North Africa's Atlas nascent mountain range, the currents attracted significant amounts of sea predators (Sharks and Rays) whose remains accumulated in this area.
Constituting close to 70% of the contents found in phosphate deposits illustrated by yellow triangles on the animated map (over Khouribga, Benguérir, Youssoufia and Boucrâa) these debris built-up during the Paleocene and Eocene epoch, some 60 to 40 Million years ago. Today, they represent by far the largest commercially mined phosphate-rock deposits available worldwide.
Further South, at the junction between Atlantic Ocean and the Sahara desert, the trade winds create a global energy exchange zone with a dry climate dominated by steady winds. Generated over the Sahara's hot surfaces, daily thermal air streams are superimposed to the Ocean's trade wind system. This generates one of the most extensive and steadiest wind regime available on earth.
Today, with funding made available by the North Atlantic Treaty Organization under its scientific collaborative frameworks with neighboring countries, complete data on wind characteristics -in particular wind speeds at various heights- have been consistently monitored on desert sites throughout Morocco and Mauritania. Established through a regional academic research and industrial partnership in support of the Sahara Wind project these measurements confirmed the exceptional quality and scale of the trade winds blowing over North Africa's coastline.