one of the regular periodic fluctuations in the density of the visible baryonic matter of the universe

(meteorology) The largest element of the intraseasonal variability in the tropical atmosphere: a large-scale coupling between atmospheric circulation and tropical deep convection, manifesting itself most clearly as anomalous rainfall.

(meteorology) The difference in pressure between the Azores High and the Icelandic Low, which changes periodically and controls the strength of the Westerlies. Usually abbreviated NAO.

A quasiperiodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere

A test to identify, evaluate and locate partial discharge faults in cable insulation and accessories.