solstices— The two points in the ecliptic where the Sun reaches its maximum and minimum 

 declinations; also the times when the Sun reaches these points. The maximum north 

 declination occurs on or near June 21, marking the beginning of summer in tlie Northern 

 Hemisphere and the beginning of winter in the Southern Hemisphere. The maximum 

 south declination occurs on or near December 22, marking the beginning of winter in tlie 

 Northern Hemisphere and the beginning of summer in tlie Southern Hemisphere. 



solstitial tides— Tides occurring near the times of the solstices. The tropic range may be 

 expected to be especially large at these times. 



species of constituent— A classification depending on the period of a constituent. The 

 principal species are semidiurnal, diurnal, and long period. 



speed (of constituent)- The rate of change in the phase of a constituent, usually expressed 

 in degrees per hour. The speed is equal to 360° divided by the constituent period 

 expressed in hours. 



spring high water— Same as mean high water springs (MHWS). See spring tides or tidal 

 currents. 



spring low water— Same as mean low water springs (MLWS). See spring tides or tidal 

 currents. 



spring range (Sg)— See spring tides. 



spring tides or tidal currents— Tides of increased range or tidal currents of increased speed 

 occurring semimonthly as the result of the Moon being new or full. The spring range (Sg) 

 of tide is the average semidiurnal range occurring at the time of spring tides and is most 

 conveniently computed from the harmonic constants. It is larger than tlie mean range 

 where the type of tide is either semidiurnal or mixed, and is of no practical significance 

 where the type of tide is diurnal. The average height of the high waters of the spring tides 

 is called spring hi^ water or mean high water springs (MHWS); the average height of the 

 corresponding low waters is called spring low water or mean low water springs (MLWS). 



Ssa— Solar semiannual constituent. See Sa. 



stand of tide— Sometimes called a platform tide. An interval at high or low water when there 

 is no sensible change in the height of the tide. The water level is stationary at high and 

 low water for only an instant, but the change in level near these times is so slow that it is 

 not usually perceptible. In general, the duration of the apparent stand wiU depend on the 

 range of tide, being longer for a small range than for a large range, but where there is a 

 tendency for a double tide the stand may last for several hours even with a large range of 

 tide. 



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