The micrometeoroids in the thermosphere and mesosphere

The variation of temperature and radius of typical micrometeoroids in the low thermosphere and mesosphere is calculated theoretically, and the formation of the spherule is explained consistently with this model. The fluffy particles floating in the stratosphere is also consistent with this calculation, since the particle of radius 10 microns and initial velocity 20 km/s cannot be heated up to the sublimation temperature, even if it is not fluffy. This calculation coincides exactly heights and velocities of meteor streams. The formation of the secondary particles from the evaporated vapor is also calculated, and it is concluded that they are very few and small, compared with the primary particles. (Author)