"Meteoric phenomena" is the accepted term for the complex of physi­ cal phenomena that accompany the entry of meteoric bodies into the at­ mosphere of the earth (or of any planet). "Meteoric bodies" are usually defined as cosmic bodies observed by optical or radar techniques, when they enter the atmosphere. The limiting sensitivity of present-day radar equipment makes it possible to record meteors of up to stellar magnitude +14, while the most brilliant bolides may reach magnitude -19. On a mass 7 7 scale this corresponds approximately to a range of 10- to 10 g. How­ ever, met~or astronomy is also concerned with larger objects, namely crater-forming meteorites, or objects that cause large-scale destruction when they arrive through the atmosphere (an example is the Tunguska River meteorite). Consideration of the interaction of such objects with 12 the terrestrial atmosphere extends the mass range to 10 g. On the other hand, scientists studying fragmentation processes in meteoric bod­ 7 ies have to consider particles with masses less than 10- g, and the use of data from meteoric-particle counters on rockets and artificial satel­ lites, from microcraters on the lunar surface, and from noctilucent clouds 12 lowers the minimum mass to 10- g. Therefore, the mass range of meteoric bodies, or meteoroids, encompasses 24 orders of magnitude. Although recent years have witnessed considerable development in meteor research, both in the Soviet Union and elsewhere, the main mono­ graphs on meteor physics were published twenty or more years ago.

Inhalt

1. General Information about Meteoric Phenomena.- 2. Historical Review of Research in Meteor Physics.- I. The Simple Physical Theory of Meteors.- 3. Fundamental Equations.- 4. Self-Similarity of the Problem of Motion and Ablation of a Meteoroid.- 5. The Problem of Meteoroid Motion with Variable Coefficients.- 6. Flow Regimes.- 7. Parameters of the Fundamental Equations.- II. The Heating of Meteoroids and the Onset of Vaporization.- 8. The Heating of a Meteoroid in the Upper Section of its Path.- 9. The Transition to Intensive Evaporation.- 10. Shielding Effects. The Regime of First Collisions.- 11. Shielding in the Transition Regime.- 12. The Case of Strong Shielding.- III. Ablation of Meteoroids.- 13. Two Main Mechanisms of Ablation: Vaporization and Spraying or Blowoff of the Molten Layer.- 14. Experimental Studies of Ablation.- 15. Theoretical Studies of the Ablation of Large Bodies.- 16. Large-Meteoroid Vaporization under the Influence of the Radiation Flux.- 17. Formation of an Ablational Shock Wave and the Energetics of Large Meteoroids.- 18. Ablation and Meteorite Morphology.- IV. Luminosities and Spectra of Meteors.- 19. The Nature of Meteor Radiation.- 20. The Luminosity Equation and its Parameters.- 21. Experimental Determinations of the Radiative Efficiency.- 22. The Effect of Meteoroid Flight Condition on the Radiative Efficiency.- 23. The Qualitative Analysis of Meteor Spectra.- 24. The Quantitative Analysis of Meteor Spectra. The Curve-of-Growth Method.- 25. Determination of the Chemical Compositions of Meteoroids from their Spectra. Comparison with Meteorites.- 26. Some Unusual Emissions.- V. Meteoric Ionization.- 27. Formation of the Ion Trail.- 28. Classification of Meteor Ion Trails.- 29. Disintegration of the Ion Trail.- 30. The Head Echo and its Relation to other Phenomena.- VI. Masses and Densities of Meteoroids.- 31. Dynamic Masses.- 32. Photometric Masses.- 33. The Hypothesis of Dustballs and Friable Meteoric Bodies.- 34. Explanation of the "Mass Paradox" as an Effect of Fragmentation.- 35. Determination of the Mineralogical Densities of the Meteoroids.- 36. Determination of the Densities of Large Meteoroids from their Breakup Heights.- VII. Fragmentation of Meteoroids.- 37. Observational Data on Meteoroid Fragmentation.- 38. Effect of Fragmentation on the Photometric Curve.- 39. Meteor Bursts.- 40. Fragmentation of Meteorites.- 41. Physical Aspects of Meteoroid Fragmentation.- Appendixes to the English Editions.- 1. A Quasi-Simple Ablation Model for the Entry of Large Meteoroids into the Atmosphere.- 2. Transfer of the Shock-Wave Radiation to the Body of the Meteoroid.- 3. Electrophonic Phenomena during the Flight of a Bright Bolide.- 4. The Dynamics of Meteoroid Breakup.- References for Appendixes.- References.