This freaky phenomenon is ball lightning.

这种奇异的现象被称作球形闪电。

Ball lightning seems an obvious explanation, says Dr Hughes.

休斯博士说，球状闪电似乎是个明显的解释。

One strange form of lightning is called ball lightning.

球状闪电是一种奇怪的闪电类型。

This highlights a problem faced by people proposing theories of ball lightning .

这使得球状闪电理论的提出者所面临的一个问题凸显出来。

Ball lightning sometimes rolls along the ground until it crashes into a tree or high wall.

有时，球状闪电在地上滚动，发出巨大的声响，直到碰到树木或高墙为止。