Fig. 4From: Vertical fine structure and time evolution of plasma irregularities in the Es layer observed by a high-resolution Ca+ lidarInstability-like structures were observed at around 100 km. A “cats-eye” structure that is suggestive of large-scale deformation by neutral dynamical (Kelvin–Helmholtz) instability is clearly seen at 99.5–102 km at 17:17–17:19 UTBack to article page