Where does turbulence collide?

The irregular, eddying regime of fluid motion that sets in at high Reynolds number, where inertial forces overwhelm viscous damping and the flow breaks into a hierarchy of swirling scales. Reynolds's 1883 experiments showed that orderly laminar pipe flow gives way to this sinuous, mixing motion once a dimensionless velocity threshold is crossed, and Kolmogorov's 1941 theory described how kinetic energy cascades from large eddies down to the smallest scales, where viscosity dissipates it as heat. The referent is a physical flow state of a real fluid, governed by the Navier-Stokes equations and quantified by velocity statistics, not a metaphor for a shaky market, a rough flight, or a burst of volatile returns.[1][2]

Unit

A flow regime of a fluid, indexed by Reynolds number and velocity fluctuation statistics

Recovery means

Damped only by molecular viscosity at the smallest scales, where the energy cascade terminates in heat

Measured by

Characterized by the Reynolds number, velocity spectra, and the Kolmogorov -5/3 spectral slope recovered from hot-wire or laser anemometry

The rate, unpredictability, and instability of change in the external environment that surrounds an organization, treated as a property of the field rather than of any single firm. Emery and Trist's 1965 account of the causal texture of organizational environments distinguished placid fields from turbulent ones, in which the ground itself is in motion and consequences arise from the interaction of many actors at once. Jaworski and Kohli's 1993 study operationalized the idea as market turbulence and technological turbulence, the pace at which customer preferences and technologies shift. The referent is a perceived condition of a market or sector, measured by managers' ratings and change indices, not a physical flow, a rough flight, or a statistical return anomaly.[3][4]

Unit

A perceived rate of change in an organization's environment, on managerial rating scales

Recovery means

Not applicable

Measured by

Assessed with survey scales of market and technological turbulence, or with indices of the volatility of demand and technology

The chaotic small-scale motion of the atmosphere that buffets an aircraft in flight, felt as sudden vertical accelerations and experienced by passengers as bumpiness. Cornman, Morse, and Cunning's 1995 method estimates its severity from in-situ aircraft measurements as the eddy dissipation rate, an aircraft-independent measure of how strongly the air is churning. The referent is atmospheric motion characterized by its effect on a moving aircraft, including clear-air turbulence that strikes in cloudless sky, and it is defined by the airframe's response rather than by a laboratory flow, an unstable market, or a return distribution.[5]

Unit

Atmospheric churning as felt by an aircraft, reported as the eddy dissipation rate

Recovery means

Not applicable

Measured by

Estimated from aircraft accelerometer and airspeed data as the eddy dissipation rate, or forecast from numerical atmospheric models

A market regime in which asset prices behave abnormally, with returns that are unusually large, unusually volatile, or decoupled from their normal correlations. Kritzman and Li's 2010 financial turbulence index measures this as the statistical distance of a period's returns from their historical average and covariance, so that both extreme moves and broken correlations register as turbulence. The referent is a quantified property of a return distribution across assets, used to flag stressed markets and to manage risk, and it shares nothing with an eddying fluid, a bumpy flight, or an organization's shifting environment beyond the word itself.[6]

Unit

A market's return abnormality, as a statistical distance of returns from their historical distribution

Recovery means

Not applicable

Measured by

Computed as the Mahalanobis distance of a period's asset returns from their historical mean and covariance