The shoreward movement of the wave thus forms a current whose net flow is parallel to the shore in the surf zone. The speed of the longshore current increases as the waves get larger and strike the beach with less frequency at a greater angle. The slope of the beach can also affect this current. Once established, the current moves at a speed of about one knot in the same direction as the advancing wave train. Longshore currents are more prevalent along lengthy straight coastlines.
Sandbars often form in areas where longshore currents frequently occur.
Rip currents are formed when longshore currents, moving parallel to the coastline, are deflected seaward by bottom irregularities, or meet another current deflecting the flow seaward. Development depends upon wave conditions. Tides Tides are the slow, periodic rise and fall of the sea surface. They are usually described as being either diurnal or semi-diurnal. Tidal ranges along the shoreline vary by location.