FAR-INFRARED OBSERVATIONS OF TRAVELING STRATOSPHERIC DISTURBANCES

Travelling ionospheric disturbances (TID) have been reported by variou s authors in the past: they have been observed in the ionosphere by me ans of indirect techniques, like disturbances in the propagation of ra dio-waves. Mesospheric disturbances, like noctilucent clouds, (NLC) ha ve been also widely quoted in literature, being observed through the S unlight scattering in night time. We present observations of TSD (trav elling stratospheric disturbances) during the stratospheric balloon pr ogram ULISSE devoted to the study of sky brightness in the wave-length region 300-3000 micron. The observed TSD appear to be localized at a, typical altitude of 80-150 km with peculiar velocities of 50-200 m se c(-1). Spectral properties of the emitted radiation have been investig ated by means of multichannel photometers: two types of TSD have been found. The first one has a spectral emissivity consistent with the sta ndard stratospheric composition (H2O and O-3 being the most important emitters): the second type of TSD, observed about one month after St. Helen explosion in 1980, has the typical spectrum of dust with an emis sivity epsilon similar or equal to l/lambda, and an abundance of the o rder of 10 particles per cm(-3) with submicron radius.