Which material occupies the fourth position in the radar reflectivity order?

• A. Concrete
• B. Earth
• C. Wood
• D. Masonry

Answer: (D)

Radar reflectivity is determined by how much radar energy a material backscatters, which depends on its dielectric properties and surface roughness. Materials with higher dielectric constants and rough, irregular surfaces return more energy.

Among these four materials, wood has the weakest backscatter due to its low density and permittivity. Earth reflects more because of moisture and unevenness. Concrete is denser and rougher still, producing stronger backscatter than wood and earth. Masonry, such as brick or stone with minerals and often higher moisture content, tends to yield the strongest backscatter of the group, so it sits last in a lowest-to-highest reflectivity order. That makes masonry the fourth.