Water science news, explainers, and statistics covering freshwater, hydrology, lakes, rivers, groundwater, ice, and Earth’s connected water systems.
A pycnocline is an ocean layer where density increases rapidly with depth. Lighter water sits above it and denser water lies below, so the layer acts as a transition between parts of the ocean that do not mix easily. The name comes from Greek roots for density and slope. Ocean density depends mainly on temperature…
More
A tidal bore is a steep wave front that travels upstream when a rising tide is forced into a shallow, narrowing river or estuary. Instead of the water level rising gradually, the flood tide arrives as a visible surge. Some bores resemble a low rolling step, while the largest form breaking waves that can be…
A rogue wave is an unusually large, steep wave that appears among much smaller surrounding waves. Oceanographers commonly use a threshold of more than twice the significant wave height, the average height of the highest one-third of waves in a measured record. The definition makes rogue waves relative to the sea state rather than dependent…
Deep-water and shallow-water waves are classified by comparing water depth with wavelength, not by judging whether the sea looks deep or shallow. A wave behaves as a deep-water wave when depth is greater than half its wavelength. It behaves as a shallow-water wave when depth is less than one-twentieth of its wavelength. Between those limits…
