Ocean Currents

**1. Rotation of the Earth:** The rotation of the Earth, also known as the Coriolis effect, influences the direction of ocean currents. In the Northern Hemisphere, currents are deflected to the right, while in the Southern Hemisphere, they are deflected to the left. **2. Air Pressure and wind:** Wind-driven currents, which are caused by the wind blowing across the surface of the ocean, are one of the primary types of ocean currents. Changes in air pressure can also affect ocean currents. **3. The density of ocean water:** Density-driven currents, also known as thermohaline currents, are caused by differences in the density of ocean water. The density of ocean water is influenced by temperature and salinity. **4. Revolution of the Earth:** The revolution of the Earth refers to the Earth's orbit around the Sun, which causes the change of seasons. However, it does not directly influence the ocean currents. Therefore, the factors that influence the ocean currents are the rotation of the Earth, air pressure and wind, and the density of ocean water.

The most important fishing grounds of the world are found in the regions where warm and cold oceanic currents meet.  Here's why: **Nutrient-rich waters:** When warm and cold currents converge, a process known as upwelling occurs. This upwelling brings nutrient-rich deep ocean water to the surface. These nutrients act like fertilizer for plankton, which forms the base of the marine food chain. **Abundant Marine Life:** The abundance of plankton attracts a vast array of fish species, making these areas highly productive fishing grounds. **Examples include:** 1. The Grand Banks (Newfoundland) - Labrador Current (cold) meets the Gulf Stream (warm) 2. The Humboldt Current (South America) - Cold, nutrient-rich current flowing up the western coast 3. The Canary Current (West Africa) - Cold, nutrient-rich current flowing up the western coast

The eastward flow of the equatorial counter-current is explained by the convergence of the two equatorial currents: * The North Equatorial Current flows westward north of the equator. * The South Equatorial Current flows westward south of the equator. The convergence of these two westward-flowing currents in the equatorial region causes an upwelling of the subsurface water, resulting in the formation of the eastward-flowing equatorial counter-current.