Jäännöspöyry

Jäännöspöyry is a Finnish term that translates to "residual turbulence" or "wake turbulence" in English. It refers to the disturbed air left behind an aircraft after it has passed. This disturbed air is a result of the aircraft's wings generating lift. As air flows over the top of the wing, it travels faster than the air flowing underneath, creating lower pressure above the wing and higher pressure below. This pressure difference causes air to flow from the wingtips inward and upward, creating swirling vortices.

These vortices are strongest at the wingtips and trail behind the aircraft. They can persist for several minutes and extend for many miles, depending on the size and weight of the aircraft, its speed, and atmospheric conditions. Larger, heavier aircraft, and those flying at lower speeds and higher angles of attack, generate stronger vortices.

The primary concern with jäännöspöyry is its potential hazard to other aircraft, particularly smaller ones. If an aircraft encounters the wake of a larger aircraft, it can experience significant rolling moments, loss of altitude, and potential loss of control. Air traffic control procedures are designed to maintain safe separation distances between aircraft to mitigate this risk. Pilots are trained to be aware of wake turbulence and to take appropriate evasive action if necessary. Jäännöspöyry is a significant factor in airport operations and air traffic management.