Abstract
Noctilucent (night-shining) cloud (NLC), which is often called polar mesospheric cloud (PMC) also, consists of water-ice particles with approximate radii of 10–50nm, usually being formed in the polar summer mesopause region (82–85km altitude). Ground-based visual, lidar, and radar observations and space missions as well as model/theoretical research have been carried out to clarify the NLC/PMC's climatology, characteristics, and formation mechanisms, extending the observations to mid latitudes in both hemispheres. The influence to global warming is controversial to some extent, while a significant correlation between 11-year solar cycle to NLC variation is suggested. Through the radar studies of “polar summer mesosphere echo (PMSE)”, the NLC particles' important role has been recently stressed, leading to new “dusty plasma” sciences in the weakly-ionized upper atmosphere.
