sonde

Sonde is a term used in science, engineering and medicine to denote a device designed to observe, sample or measure properties within a medium or system. The word originates from French, where sonde means probe or sounding instrument, and in English it is used especially in technical contexts to describe measurement probes or sensing assemblies.

In atmospheric science, radiosondes are lightweight instruments carried aloft by weather balloons to record parameters such as temperature, humidity, pressure and wind speed. Data are transmitted back to the ground for atmospheric profiling. Other atmospheric sondes include ozonesondes and aerosol sondes, which monitor specific gases or particulates.

In oceanography and hydrology, sondes are deployed to measure conductivity, temperature, depth, salinity and related properties. CTD sondes connect sensors to ship-based instruments or moorings. Downhole and borehole sondes log geophysical or water properties within wells and rock formations for scientific or industrial purposes.

In engineering and industry, various downhole, borehole, or contact sondes are used to assess material properties, corrosion, thickness, or moisture content. Medical practice also uses the term; a sonde can refer to a catheter, probe or instrument inserted into the body for diagnostic, therapeutic or monitoring purposes, especially within French-language contexts.

In space exploration, the term is used in several languages to denote space probes or atmospheric entry probes, often as a translation of space probe (sonde spatiale in French). Overall, sondes are purpose-built instruments integrated with sensors, data loggers, and communication systems to collect environmental or physiological information.