# Wake turbulence Wake turbulence is the disturbed air an aircraft leaves behind — dominated by the pair of counter-rotating [[Wingtip_vortices]] shed as the price of lift. It is invisible to radar, it persists for minutes, and it can roll a following aircraft faster than its [[Control_system|controls]] can answer. That combination makes it an operational hazard rather than an academic one, and the reason air traffic is spaced by weight class rather than by distance alone. ## Behaviour in the real atmosphere The two [[Vortex|cores]] sink a few hundred feet below the generating aircraft's path and drift with the [[Atmosphere_of_Earth|wind]]. Near the ground they stop descending and roll outward, and a light crosswind can hold one stationary over a parallel runway — the worst case, because it neither decays nor departs. Decay comes from the Crow instability, in which the two cores develop a sinusoidal wobble, touch, and reconnect into a chain of rings; ambient [[Turbulence]] and thermal stratification speed that up, so quiet stable air is the dangerous condition. ## Measuring and spacing Lidar scans reduce a wake to a core radius and a [[Circulation_(physics)|circulation]], usually via a [[Rankine_vortex]] fit, and separation minima are computed from how that circulation decays. Because the minima gate runway throughput, wake physics is a capacity constraint for [[Aviation]] and a live [[Avionics|flight-deck]] procedure, not just a safety margin. Helicopters and [[WT!Energy_Center_of_Excellence|wind turbines]] generate their own versions — in a wind farm the wake of one machine is the inflow of the next, which is why spacing there is an [[Mathematical_optimization|optimisation]] problem. **Microsim brief (next pass):** Top-down runway with a generating aircraft and a crosswind slider; the vortex pair drifts, sinks, and either clears or parks over the parallel runway. Follower aircraft shows a roll indicator. **On the spine:** [[Wingtip_vortices]] · [[Rankine_vortex]] · [[Circulation_(physics)]] · [[Turbulence]] · [[Vortex_ring]] · [[WT!Thury_Hydrodynamics_Compendium]]. ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Wake_turbulence) : [Wikitube](https://en.wikitube.io/wiki/Wake_turbulence) ## Previous hub tags Hubs: `Life_Physics`, `Systems`. Portals: [[PORTAL_WT!Thury_Hydrodynamics_Compendium]], [[PORTAL_Aviation]], [[PORTAL_Avionics]], [[PORTAL_Reliability_engineering]]. --- *Fluid seed wave · 2026-09-10 · seed register · microsim layer pending.*