The word "tides" is a generic term used to define the alternating rise and fall in sea level with respect to the land, produced by the gravitational attraction of the moon and the sun. The term tide correctly refers only to a relatively short period, astronomically-induced change in the height of the sea surface: the expression tidal currents relates to accompanying periodic horizontal movements of the ocean water, both near the coast and offshore (but distinct from the continuous, stream flow type of ocean current.)
These astronomically driven tidal waves which move up and down the Chesapeake Bay are easily predicted. Tide tables contain these predictions and are essential tools for marine navigation, fishing, and other water-dependent activities. Additional non-astronomical factors, such as the configuration of the coast line, local depth of the water, bathymetry, and other hydrographic and meteorological influences play an important role in altering the range interval between high and low water, and the times and arrival of the tides.
