No abstract

A description is given of the design of an instrument which has been built to detect the lithium 671 nm line against the daytime sky continuum. The instrument covers the field of view by means of a servocontrolled scanning mirror and detects the lithium line by chopping the received beam and using phase sensitive detection. Data obtained for a daytime release of lithium between 90 and 130 Ian altitude are presented, and the methods for the analysis of these data to obtain a wind profile of the upper atmosphere are described. The derived wind profile is similar in its main features to those observed at twilight and night.

SummaryGlows have been observed at Woomera when grenades ejected from Skylark rockets have been detonated in the altitude range 90-170 km. Using results obtained from these glows by a special scanning photometer located on the ground, an estimate has been made of the diffusion coefficient in the region 120-160 km. The theoretical model which is used to describe the behaviour of the explosion products incorporates the assumptions of molecular diffusion, a Gaussian distribution of particle density, and an optically thin cloud. The effects of consumption of the cloud particles are included in the model.

SummaryRecords of the behaviour of aluminized grenade glow clouds at twilight and at night were obtained using cameras and photometers. From these records the radiance, radiant p~wer, and radiant energy have been deduced for the altitude range 100-200 km. The twilight observations show that the absorption cross section of aluminium monoxide is about 3 X lO-14 cm2• From the night-time results it is concluded that the glow probably arises from a chemiluminescent reaction with atomic oxygen. A set of reactions consistent with the observations above 120 km altitude is AI02 +O -+ AIO+02, AIO+O -+ AI02+hv, AIO+O -+ AI+02, with the rate constants being 5 X 10-12, 1 X 10-13, and 4 X 10-13 cm3 molecule-1 sec-1 respectively.

SummaryA discussion is given of the time variation in radiance which would be observed across a diffusing glow cloud released in the upper atmosphere. A Gaussian distribution for the contaminant number density is used, and it is assumed that, when chemical reactions occur, either the contaminant density is everywhere very small, or an insignificant quantity of contaminant is consumed.The cases of chemiluminescence and scattering of the Sun's rays are examined, and the effects on the observed radiance of absorption, re-emission, and scattering of radiation within the cloud are considered. The results may be used to interpret observations on upper atmosphere contaminant releases. It is found that if the cloud is optically thin the radiance distribution is Gaussian for both chemiluminescent and sunlit glow clouds, and the radiance is proportional to the number of cloud particles along the line of sight. Optically thick glow clouds will not be Gaussian, and it is inadmissible to use a method based on a Gaussian distribution in analysis of these clouds.