A program has been developed that portrays the fractal modeling of lightning, which subsequently calculates the fields from a fractal antenna. Nodal currents are weighted with branch length. The Hausdorff dimension for various growth parameters η, agree with those in the literature. Electric fields in the far zone have been calculated by weighting the branch currents with an overall damped sinusoidal current. The current waveform for each element is evaluated at retarded times based upon the speed the discharge propagates along the fractal. At scale lengths of 100 m an interference pattern becomes noticeable. We have investigated the slope of the power spectrum for spider lightning. For f < fthreshold the slope is between -1.6 to -2.6 with a standard deviation of ~ 2. In the case of channel lightning this slope would be -2. For f > fthreshold the average slope varies between -3.4 and -3.5. In the case of channel lightning this slope would be -4. The lesser slope is attributed to more interference between radiating elements in this model. For f > fthreshold the slope appears to be independent of the growth parameter. Observations show for inter-cloud lightning the threshold frequency is 50 kHz, with zero slope for f < fthreshold and -1.6 slope for f > fthreshold.
Level of Degree
Physics & Astronomy
First Committee Member (Chair)
Second Committee Member
Los Alamos ISR-2 group
Lightning--Computer simulation, Fractals.
Greninger, Paul. "Fractal modeling of lightning." (2011). http://digitalrepository.unm.edu/phyc_etds/19