Noctilucent clouds have been hypothesized to be composed of dust particles which are enlarged by sublimation of water vapor. A meteoritic origin of the solid particles has been questioned on grounds of lack of the proper asymmetry in meteor dust impact. Reevaluation of this factor indicates that there is a marked latitudinal gradient which will result in significantly higher concentrations in the polar regions. Also, analysis of Meteorological Rocket Network wind data shows a poleward meridional flow centered at the stratopause which is assumed to diverge upward in the noctilucent cloud latitudes and to provide the reduced fall rate required for development of the observed high particulate concentrations. There is a possibility that moisture‐enriched low‐latitude stratospheric air is advected and condensed by this meridional and vertical flow system. The occurrence of noctilucent clouds is consistent with available data, and they are our most efficient natural probes of stratospheric and mesospheric circulations.
From the inception of the Meteorological Rocket Network, the Meteorological Working Group of IRIG has been a convenient mechanism for coordinating the Network activities of the several participants. Upper atmospheric observation activities of the contributing agencies and projects have thus been coordinated to form the first synoptic-type study of the atmospheric region accessible only by rocket observation techniques. The Meteorological Rocket Network Committee (MRNC) has served as a forum for planning of studies, assimilating data on new developments in rocket vehicles, telemetry and sensing systems, and the distribution of the resulting data. The progress of the growing Meteorological Network is charted to date, and several of the applications of the resultant data are indicated. The impact of the Meteorological Rocket Network on the meteorological profession is discussed.
Diurnal heating of the ozonosphere near the stratopause level results in a diurnal temperature variation of approximately 15°C and development of a tidal circulation in the stratospheric wind field. This tidal circulation is hemispherically separated over the equator by earth rotational effects and rises into the mesosphere at high latitudes as a result of oblique incidence of solar radiation. Winds of the tidal circulation are principally meridional in middle latitudes—poleward ahead of the crest of the heat wave and equatorward in the afternoon and evening. At high latitudes the circulation is zonal around the poleward end of the heated ridge—westerly as the turn is made short of the pole in the winter situation and easterly in summer when the heated ridge includes the polar region. It is postulated that solar input energy to the general stratospheric circulation is redistributed by this tidal circulation, and that vertical winds of this tidal circulation are responsible for the support of noctilucent cloud particles and special ionospheric electrical phenomena such as the equatorial electrojet.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.