Serein

The fall of rain from an appar¬ently clear sky. The phenomenon may be explained by the evaporation of cloud par¬ticles following the formation of rain droplets, or by the movement of cloud away from the overhead position as the rain approaches the ground. serlr A veneer of mixed sand and gravel mantling a Saharan plain and transported originally by "sheet-wash and *braided-stream activity. Subsequently it was weathered and modified under more arid conditions.