“…The risetime (RT) of lightning current is assumed to be 5h/c. Note that, when the lightning strikes the 50-m-tall object, RT is about 0.8 μs (5h/c), a typical subsequent return stroke with relatively more high frequency (e.g., Qie et al, 2007Qie et al, , 2009Qie et al, , 2014Wang et al, 2012;Yang et al, 2008Yang et al, , 2010Zhang et al, 2009), the corresponding field attenuation along the finitely conducting ground is more (see Fig. 6(b)), because the presence of tall objects tends to further increase higher frequency contents, and the field propagation attenuation for lighting strike to tall objects mainly depends on the height of tall objects, the earth conductivity and the current RT.…”