Which environmental factor is noted as allowing longer radar range in calm seawater?

• A. Rough seas interfere with propagation.
• B. Calm seawater conductivity allows longer-range propagation.
• C. High humidity always blocks radar.
• D. Wind shear near the surface increases loss.

Answer: (B)

The factor being tested is the way the air–sea boundary supports a surface-propagating path. When seawater is calm and its boundary with air is smooth, the radar energy can travel along the interface more efficiently rather than being scattered or dissipated by rough waves. Seawater’s conductivity helps establish and sustain this boundary-driven, surface-bound propagation, allowing the signal to follow the surface farther and with less loss. In rough seas, the surface irregularities scatter the energy and increase attenuation, shortening the range. Humidity or wind shear aren’t the primary drivers for extending range in calm conditions, so they don’t produce the same effect.