A body of water has a natural period of oscillation, dependent upon its dimensions. None of the oceans is a single oscillating body; rather each one is made up of several separate oscillating basins. As such basins are acted upon by the tide producing forces, some respond more readily to daily or diurnal forces, others to semidiurnal forces, and others almost equally to both. Hence, tides are classified as one of three types, semidiurnal, diurnal, or mixed, according to the characteristics of the tidal pattern.

In the semidiurnal tide, there are two high and two low waters each tidal day, with relatively small differences in the respective highs and lows. Tides on the Atlantic coast of the United States are of the semidiurnal type, which is illustrated in Figure A by the tide curve for Boston Harbor.

In the diurnal tide, only a single high and single low water occur each tidal day. Tides of the diurnal type occur along the northern shore of the Gulf of Mexico, the Gulf of Tonkin, and in a few other localities. The tide curve for Pei-Hai, China, illustrated in Figure B, is an example of the diurnal type.

In the mixed tide, the diurnal and semidiurnal oscillations are both important factors and the tide is characterized by a large inequality in the high water heights, low water heights, or in both. There are usually two high and two low waters each day, but occasionally the tide may become diurnal. Such tides are prevalent along the Pacific coast of the United States and in many other parts of the world. Examples of mixed types of tide are shown in Figure C. At Los Angeles, it is typical that the inequalities in the high and low waters are about the same. At Seattle the greater inequalities are typically in the low waters, while at Honolulu it is the high waters that have the greater inequalities.

• Finding Height Of Tide At Any Time - 2009-04-04 - 12:39:33
• Tides and tidal currents - Meteorological effects - 2009-04-04 - 12:27:40
• Variations in range of the tide - 2009-04-04 - 12:04:10
• Causes Of Tides - 2009-04-04 - 11:35:09
• Tides and tidal currents - Computer Predictions - 2009-04-03 - 10:33:27
• Current Diagrams - 2009-04-03 - 11:02:50
• Tidal Current Charts - 2009-04-03 - 10:40:48
• Duration Of Slack Water - 2009-04-03 - 10:27:11
• Tidal Current Predictions For Subordinate Stations - 2009-04-03 - 10:20:54
• Tidal Current Prediction For Reference Stations - 2009-04-03 - 10:10:24

• < Prev
• Next >