Science / Tides and Currents / Type Of Tide: A classification based on characteristic forms of a tide curve. Qualitatively, when the two high waters and two low waters of each tidal day are approximately equal in height, the tide is said to be semidiurnal; when there is a relatively large diurnal inequality in the high or low waters or both, it is said to be mixed; and when there is only one high water and one low water in each tidal day, it is said to be diurnal. Quantitatively (after Dietrich), where the amplitude ratio of K1 + O1 to M2 + S2 is less than 0.25, the tide is classified as semidiurnal; where the ratio is from 0.25 to 1.5, the tide is mixed, mainly semidiurnal; where the ratio is from 1.5 to 3.0, the tide is mixed, mainly diurnal; and where greater than 3.0, diurnal.
Type Noun Synonyms: class, category, classification, kind, sort, genre, order, variety, breed, species, strain, group, genus, ilk, kidney
Type Adjective Synonyms: typewrite, keyboard, transcribe
Science / Tides and Currents / Neap Tides Or Tidal Currents: Tides of decreased range or tidal currents of decreased speed occurring semimonthly as the result of the Moon being in quadrature. The neap range (Np) of the tide is the average range occurring at the MORE
Science / Tides and Currents / Tidelands: The zone between the mean high-water and mean low water lines. It is identical with intertidal zone (technical definition) when the type of tide is semidiurnal or diurnal. MORE