Sources of energy – currents

The term current refers to permanent or seasonal movement of surface water in seas and oceans. The three main types of current are longshore currents, rip currents and upwelling.

Longshore currents: also called littoral drift – occur as most waves approach shoreline at an angle – generates flow of water (current) running parallel to shoreline

Rip currents: strong currents moving away from shoreline – develop when seawater is piled up along coastline by incoming waves – current may start flowing parallel to the coast before flowing out through breaker zone

Upwelling: movement of cold water from deep towards the surface – denser cold water replaces warmer surface water creating nutrient rich cold ocean currents – form part of pattern of global ocean circulation currents.