Where have you been? Missed you.
>When one looks at the description on the back of a symphonic CD,
>one is likely to find each movement characterized by the tempos to
>be employed-allegro, moderato, presto, etc. Yet in an opera, sections
>tend to be designated by their form-aria, cavatina, duetto, etc. I've
>concluded that this is because most orchestral movements are composed
>of some version of sonata form. I have noticed that sometimes other
>forms are identified (and, in these cases the tempo is omitted) as with
>menuetto and trio, rondo, theme and variations, etc.
>Am I on the right track? Is this a convention with a rationale or is
>it simply tradition?
I haven't the slightest idea. I can speculate only.
I don't think most symphonic movements are necessarily variations of
sonata form. The first movement usually is, and I think that's the one
that's most often named after a tempo. I wouldn't say that other movements
necessarily have much to do with sonata form.
I would guess that a composer names a movement in a way that best
describes its character or structure, the latter when it also describes
Beyond that, I know bupkus.