How did the Rayonnant style change the appearance of Gothic churches?

The Rayonnant style, a 13th-century phase of Gothic architecture, shifted the focus of church design from achieving massive height to creating rich visual effects through elaborate decoration.12

This stylistic evolution transformed the appearance of churches in several key ways:

• Increased Glazing: Architects thinned vertical supporting members and enlarged windows, eventually merging the triforium gallery and clerestory into a single, expansive glazed area. This turned walls into undifferentiated screens of tracery, mullions, and glass.12
• Radiating Ornamentation: The style is named for the radial patterns of the rose window, which became a defining feature of French cathedral facades.12
• Decorative Emphasis: Buildings were adorned with intricate moldings and pinnacles. Furthermore, stained glass transitioned to lighter colors, which improved the visibility of tracery silhouettes and allowed more light to flood the interior.12

Notable examples of this aesthetic include Amiens Cathedral, Notre-Dame de Paris, and the Sainte-Chapelle in Paris.1