Virga is rainfall that evaporates before it reaches the ground. In the desert, Virga clouds can be present when other parts of the sky are clear. When sunlight reflects off of Virga, the visual effects are very ethereal. Here is a short video of Virga taken in 2010 that I found on YouTube:
There are two things that unify this movement. The first is the use of major 7th chords that are sometimes varied by substituting an augmented fifth or adding a ninth. These chords give an ethereal beauty to the movement. The second is the descending staccato sextuplets that diminuendo representing the falling rain evaporating.
The form of the movement is loosely A A'. Within each section, the musical material is varied through use of different motifs, instrumentation, and texture.
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