Screening of meteoroids by ablation vapor in high-velocity meteors

The ablation is calculated of non-fragmenting 10(-)2 to 10 cm sized meteoro ids for typical Leonids with a velocity of 72 km/s at altitudes of about 90 -110 km. At altitudes below the onset of intensive evaporation, a dense vap or cloud is formed around the body. This vapor cloud screens the meteoroid surface from direct impacts of air molecules. A particle beam model is deve loped that describes the air meteoroid interaction. Based on this model, th e physical parameters of the vapor cloud are calculated and compared with o bservations collected during the Leonid Multi-Instrument Aircraft Campaign. General agreement with measured temperatures is found. In addition, bounda ries of the model's applicability to specific encounter conditions are give n.