supersonisesti

Supersonisesti is a Finnish adverb meaning “in a supersonic manner” or “at speeds exceeding the speed of sound.” It is formed from the adjective supersoninen (supersonic) with the adverbial suffix -isesti. The concept refers to motion or phenomena occurring at speeds above the sonic threshold in a given medium, typically air.

In physics and engineering contexts, supersonisesti describes motion when the Mach number exceeds 1. In this regime, disturbances in the surrounding medium cannot propagate ahead of the object, leading to shock waves and, in many cases, a sonic boom. The term is commonly used in Finnish scientific and popular texts about aerodynamics, ballistics, and propulsion. It is contrasted with subsonisesti (subsonic) and, in some contexts, with hypersonisesti (hypersonic).

Examples of topics discussed in the supersonisesti regime include aircraft speeds, artillery projectiles, and bullets that travel faster than the speed of sound, as well as associated visible and audible effects such as sonic booms. The word is primarily a linguistic marker in Finnish for describing high-speed motion, but it also appears in translated scientific and journalistic writing when Finnish authors refer to speed regimes described in English-language sources.

See also: Mach number, sonic boom, supersonic flight.