Here's a video of a double slit interference experiment in water with two src.
This is similar to AM, as in, we have a carrier and info-signal.
If you look at the video - the blue water/crests/troughs represent the modulated carrier - our red-line in the wiki-image.
The upper envelope isn't distinguishable in the YT video, but one could imagine that the envelope was an imaginary surface connecting just the peaks of water which would have varying height.
The thing is, the YT video is a mechanical wave, whereas AM is an electromagnetic wave - so it's just a bunch of points that could experience some force IF there was a charged particle there. The envelope is therefore like a line of force - invisible to the naked eye.
Is this correct?