雷 léi thunder

How it came to be

Rain over a field, which in older forms was several drums in a row. The character is about the rolling: one sound following another across the sky.

Thunder - 打雷 (dǎléi) it's thundering, 雷雨 (léiyǔ) a thunderstorm, 雷声 (léishēng) the sound of thunder.
Also the tech loan 雷达 (léidá) radar. 雷同 (léitóng) = suspiciously identical/copied (answers that 雷同). Slang 雷 = shockingly cringe/over-the-top: 太雷了 (tài léi le) that's appalling. Note 地雷 (dìléi) is a landmine.