They are called rectified waveforms. The bottom, so to speak, of the traditional waveform is not displayed. On the other hand you get more information about the audio you are editing in. 

The light tops are the peaks. The dark middle is the RMS value. 

So, get for information about the audio. 

Here is a example of the amount of audio seen in Hindenburg and a traditional waveform. 

And this is the same waveform when the gain is decreased by 12 dB