TIDAL DATUM - See DATUM, CHART, and DATUM PLANE, 



TIDAL DAY - The time of the rotation of the earth with respect to the 

 moon, or the interval between two successive upper transits of the 

 moon over the meridian of a place, about 2ij..8Ii. solar hours (2h hours 

 and 50 minutes) in length or 1.03^ times as great as the mean solar 

 day, (See Figure A-IO) 



TIDAL FLATS - Marshy or muddy land areas which are covered and uncovered 

 by the rise and fall of the tide, 



TIDAL INLET - (l) A natural inlet maintained by tidal flow; (2) Loosely 

 any inlet in which tha tide ebbs and flows. Also TIDAL OUTLET. 



TIDAL PERIOD - The interval of time between two consecutive like phases 

 of the tide. (See Figure A-IO) 



TIDAL POOL - A pool of water remaining on a beach or »eef after recession 

 of the tide, 



TIDAL PRISM - The total amount of water that flows into the harbor or 



out again with movement of the tide, excluding any fresh water flow, 



TIDAL RANGE - The difference in height between consecutive high and low 

 waters, (See Figure A-lO) 



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

 (See Figure A-IO) 



TIDAL WAVE - See TSUNAMI. 



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



gravitational attraction of the moon and sun acting upon the rotating 

 earth. Although the accompanying 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 vertical movement. 



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

 tides grow later day by day. 



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

 day. (See Figure A-IQ) 



TIDE, EBB - That period of tide between a high water and the succeeding 

 low water J falling tide. (See Figure A-IO) 



TIDE, FLOOD - That period of tide between low water and the succeeding 

 high waterj a rising tide. (See Figure A-IO) 



A~35 



