Before Your Trip On the Day of Trip Back at School Ext. The measure of total dissolved substances in water is salinity. Salinity levels may vary depending upon evaporation, precipitation, and runoff from land.
Tidal changes occur daily, shown by two high tides and two low tides each day.
As a result, twice a day the intertidal zone is uncovered by the falling tides. Tides are a wave form resulting from centrifugal and gravitational interaction among the sun, moon, and earth, and the rotation of the earth. Very high and very low tides called spring tides, occur with the full and new moon when the earth, moon, and sun are aligned. Neap tides, which are moderate high and low tides, occur with the half moon phases each month when the moon and sun are at right angles to each other. Tide schedules can be found at sport fishing stores and in the newspaper.