What does horizontal shadowing describe on the radar image?

• A. It refers to a shadow caused by the sun on the radar screen.
• B. It is the radar feature that improves resolution near shore.
• C. As the vessel transits the coastline the RADAR picture changes with the shape of the closest land/shore.
• D. It describes a shadow cast by inland mountains only.

Answer: (C)

Horizontal shadowing shows up when land that's close to the radar, like the coastline, blocks part of the radar beam. That blocking creates a shadowed area on the screen whose shape follows the outline of the nearby shore. As your vessel moves along the coast, the coastline’s contour changes the pattern of this shadow, so the radar picture shifts to reflect the shape of the closest land or shore. This is not caused by the sun on the display, nor is it about improving resolution near shore, and it's not limited to inland mountains; the effect described specifically tracks the coastline as you transit it.