An ocean current is a continuous, directed movement of the seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling and temperature and salinity differences. depth contours, shoreline configuration, and interaction with other currents influence a current’s direction and strength.
ocean currents are primarily horizontal water movements.
Cold ocean currents influence the climate and environmental conditions of the adjacent land masses in the following ways;
- Cold ocean currents tend to control the temperatures of the surrounding land masses due to the influence of the land and sea breezes. E.g. the Benguela lowers the temperatures of surrounding areas in Namibia e.g. Walvis Bay has temperatures of 160C as compared to Durban’s 250C and yet they lie at almost the same latitude.
- Cold ocean currents lead to arid conditions or the formation of marine deserts on the adjacent coastal lands. This is because of limited evaporation and winds that blow over them hardly pick any moisture. The winds also generally tend to be off shore winds meaning that the level of condensation that will result into rainfall is low. Examples of marine deserts include the Namib Desert which is due to the cold Benguela current. The Californian desert is due to the cold Californian current and the Atacama Desert due to the cold Peruvian current.
- They tend to result into low humidity; this is because of the low rate of evaporation. This consequently leads to limited cloud cover because of the limited atmospheric moisture.
- Cold ocean currents lead to the formation of cold offshore fog or misty conditions as a result of rapid radiation cooling. It may also be due to when slightly warm air blows over the cold ocean currents resulting into steam fog e.g. there are frequent foggy conditions in San Francisco in southern California and in the Labrador region in eastern Canada.