Study On The Temperature Characteristics Of Ball Lightning

Ball lightning is a rare physical phenomenon in nature.It is also one of the unsolved puzzles of the world.Because the occurrence of ball lightning is unpredictable,low frequency and short time,there is a lack of scientific observation data.Although many scientists are committed to the study of ball lightning,the physical phenomena have not been explained up to now.Therefore,research on the production process and physical properties of ball lightning is of great significance to revealing the physical mechanism such as the production and energy source of ball lightning.Based on the whole process and spectrum of ball lightning recorded by two slitless spectrometers,the production process of ball lightning is analyzed in detail.Ball lightning is formed after a normal cloud-to-ground lightning hit the ground.By analyzing the high time-resolved spectrum of ball lightning,it is found that the ball lightning spectrum is quite different from the cloud-to-ground lightning spectrum.The radiation spectrum of cloud-to-ground lightning is mainly composed of nitrogen and oxygen ion lines of secondary ionization,while the atomic lines of soil elements are observed in the spectrum of ball lightning.It can be inferred that the temperature of ball lightning is much smaller than that of cloud-to-ground lightning.Spectral analysis is one of the important methods to diagnose the internal physical characteristics of lightning.In this work,the temperature and energy density of ball lightning are calculated based on the ball lightning spectrum and plasma theory.The correlation between these physical parameters and the change of size,color and light intensity of ball lightning is discussed.According to the spectral analysis and plasma theory,the temperature of ball lightning at the production time is calculated about 5000 K.Then the temperature has dropped hundreds of degrees and remains at this temperature for a long time.The evolution of temperature is consistent with the evolutions of color and size of ball lightning.Combined with the simulation experiment of luminous intensity of ball lightning,the energy density of ball lightning at stabilization period is estimated as 1.65x10~2MJ/m~3.The role of environmental conditions,soil elements and other factors in the formation of ball lightning is also discussed by combined with the physical parameters and spectral information of ball lightning.These researches provide an important basis for finding the conditions to stimulate ball lightning and also provide a reference scheme for the artificial production of ball lightning in laboratory.