Final answer:
The middle band of the nave elevation behind the aisle roof is the triforium. The clerestory is the uppermost level with windows.
Step-by-step explanation:
The middle band of the nave elevation that you are asking about is called the triforium. The roof of the aisle is located just behind this area. It is important to understand that the clerestory is the uppermost level of the nave elevation, typically consisting of a series of windows that allow light into the nave. This clerestory sits above the triforium, and they are both above the nave arcade, which is at ground level. The triforium typically has double-light openings or double, windowless arches, each pair set within a larger arch that mirrors the corresponding arch on the lower level. Understanding the layout of a traditional basilica-stylstyler church with aisles, the nave, and the transept helps to locate the clerestory as the window-filled upper part of the nave wall.