TIDAL RISE - The height of tide as referred to the datum of a chart. 

 (See Figure A-10.) 



TIDAL WAVE - (1) The wave motion of the tides. (2) In popular usage, 

 any unusually high and destructive water level along a shore. It 

 usually refers to STORM SURGE or TSUNAMI. 



TIDE - The periodic rising and falling of the water that results from 

 gravitational attraction of the moon and sun and other astronomi- 

 cal bodies acting upon the rotating earth. Although the accompany- 

 ing horizontal movement of the water resulting from the same cause 

 is also sometimes called the tide, it is preferable to designate 

 the latter as TIDAL CURRENT, reserving the name TIDE for the ver- 

 tical movement. 



TIDE, DAILY RETARDATION OF - The amount of time by which correspond- 

 ing tides grow later day by day (about 50 minutes) . 



TIDE, DIURNAL - A tide with one high water and one low water in a 

 tidal day. (See Figure A-10) 



TIDE, EBB - See EBB TIDE. 



TIDE, FLOOD - See FLOOD TIDE. 



TIDE, MIXED - See MIXED TIDE. 



TIDE, NEAP - See NEAP TIDE. 



TIDE, SEMIDIURNAL - See SEMIDIURNAL TIDE. 



TIDE, SLACK - See SLACK TIDE. 



TIDE, SPRING - See SPRING TIDE. 



TIDE STATION - A place at which tide observations are being taken. It 

 is called a primary tide station when continuous observations are 

 to be taken over a number of years to obtain basic tidal data for 

 the locality. A secondary tide station is one operated over a 

 short period of time to obtain data for a specific purpose. 



TIDE, STORM - See STORM SURGE. 



TOMBOLO - A bar or spit that connects or "ties" an island to the main- 

 land or to another island. (See Figure A-9.) 



TOPOGRAPHY - The configuration of a surface, including its relief, the 

 position of its streams, roads, building, etc. 



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