These jets are common features for all studied meteors. When these meteoroids reached 130 km height, their diffuse structures of the radiation quickly transformed to the usual meteor appearance resembling moving droplets, and meteor trains started to develop. These meteor phenomena were not recognized before our observations. Differential ablation of sodium atoms in faint Leonid meteors was discovered using the video spectroscopy. We interpret this fact in the framework of the dust ball model of Hawkes and Jones.
Sodium appears to be a part of relatively volatile glue which holds together silicate grains.
The glue evaporates soon and the grains then continue their flight individually. This effect is typical for Leonids but is present in some other meteors, too. The first video spectra of meteor persistent train were obtained during the 1999 airborne Leonid campaign. The spectra enabled us to derive the temperature in the first seconds of the train formation. The temperature dropped from 5000 K to 1200 K during two seconds.