Nurklise

Nurklise refers to a phenomenon observed in certain types of underwater acoustics, particularly in marine environments where sound propagation is influenced by the ocean’s physical properties. The term originates from the Finnish word "nurkkeli," meaning "corner" or "nook," which metaphorically describes how sound waves can become trapped or concentrated in specific regions of the ocean. This effect is closely related to acoustic channeling, where sound waves are confined within layers of water with varying densities, temperatures, or salinity.

Nurklise is most commonly associated with the behavior of low-frequency sound waves in the deep ocean. These waves can travel long distances with minimal attenuation due to the presence of a sound channel, often called the deep sound channel or SOFAR (Sound Fixing and Ranging) channel. This channel forms when the speed of sound in water increases with depth to a certain point and then decreases, creating a waveguide that traps sound waves. Under certain conditions, sound can become trapped in these channels, leading to unexpected concentrations of acoustic energy in localized areas, hence the term "nurklise."

The phenomenon is significant in fields such as oceanography, marine biology, and underwater communication. It can affect the detection of marine life, the spread of noise pollution, and the performance of sonar systems. Researchers study nurklise to better understand sound propagation in the ocean, which has implications for navigation, underwater surveillance, and the assessment of environmental impacts from human activities like shipping or seismic surveys. While the term is not widely used outside of Finnish or specialized marine science circles, it highlights the intricate ways sound behaves in complex underwater environments.