640. When making landfall at night, the light from a powerful lighthouse may sometimes be seen before the lantern breaks the horizon. Which term describes this light?

Loom describes the diffused glow of a powerful light, such as a lighthouse, visible over the horizon before the light source itself is seen. This navigational phenomenon results from atmospheric scattering and refraction, and is a recognized term in maritime practice, unlike elevation, diffusion, or backscatter.