Radar imagery interpretation is difficult and variable without ground truthing.
It is not based on a spectral response that we are similar with (visible, infrared or thermal) but is instead based on polarized microwaves. What this means is that it is sensitive to the roughness and orientation and nature of the ground surface.
Radarsat can transmit and receive waves that are horizontally or vertically polarized. Horizontally polarized waves are more likely to strongly pick up horizontal perpendicular features.