Waves and tides

Wave Crest

The highest point of a wave above the still-water level

Wave Trough

The lowest point of a wave below the still-water level

Wave Height (H)

The vertical distance between the wave trough and the wave crest

Wavelength (L or λ)

The horizontal distance between two consecutive crests or two consecutive troughs

Wave Period (T)

The time it takes for two consecutive wave crests to pass a fixed point

Wave Frequency (f)

The number of wave crests passing a fixed point per unit of time (1/Period)

Still-Water Level

The average sea surface elevation in the absence of waves; halfway between crest and trough

Wave Base

The maximum depth to which wave energy penetrates, equal to 1/2 the wavelength (λ/2)

Fetch

The distance of open water over which wind blows unimpeded to generate waves

Shallow-Water Wave

A wave entering water shallower than 1/2 its wavelength, causing bottom friction and breaking

Tsunami

Long-period sea wave caused by undersea earthquakes, volcanic eruptions, or landslides

Spring Tides

Tides with the largest tidal range; occur during New and Full Moons when Sun, Moon, and Earth align

Neap Tides

Tides with the lowest tidal range; occur during 1st and 3rd Quarter moons at 90-degree angles

Diurnal Tide

Tidal pattern featuring one high tide and one low tide per lunar day

Semidiurnal Tide

Tidal pattern featuring two high tides and two low tides of equal height per lunar day

Mixed Semidiurnal Tide

Tidal pattern featuring two high tides and two low tides of unequal height per lunar day