Year: 2025
Type: preprint
Abstract: In this paper, we demonstrate that sprites (a form of high-altitude, branching electrical discharge) exhibit multifractality. Multifractals are a type of fractal – geometric objects with fine structure at arbitrarily small scales. Multifractals have a more complex distribution of mass (pixel brightness) than monofractals, and so are characterized by a multifractal dimension spectrum, rather than a single fractal dimension. The multifractal spectrum is a quantitative signature of a fractal, which allows us to empirically compare and contrast sprites. We calculate the multifractal spectra of two sprites from photographs. To use all the information available in our photographs, we developed a method that incorporates pixel brightness. Both sprites had similar spectra with a range of about 4 to 1.7, which indicates strong multifractality. There is a small difference between the spectra on the positive side, which indicates that the brightest region of one of the sprites is more singular than that of the other sprite. This methodology can be adapted to compare simulated sprites to natural sprites, which can be used to test the underlying assumptions of numerical models of sprites.
Authors: Payson Atticus Gough, Ningyu Liu
Institution: University of New Hampshire
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W4413981767