Final answer:
In Vivaldi's Spring, the orchestral ritornellos alternate with the mostly solo violin concertino.
Step-by-step explanation:
In Vivaldi's Spring, the orchestral ritornellos alternate with the mostly solo violin concertino. The concertino is a small group of solo instruments that contrasts with the larger orchestral group, known as the ripieno. In Vivaldi's Spring, the concertino consists mainly of the solo violin, which plays virtuosic and expressive melodies that depict the sounds and imagery of spring.