In cities with wetter climes, storms are cautiously observed through windows. In droughty Los Angeles, they’re ogled in a museum. Rain Room, an exhibition that simulates a downpour indoors, opens at LACMA on November 1. The high-tech installation is immersive: Up to seven people at a time can walk through the 1,000-square-foot deluge without getting wet. British studio rAndom International, whose experiential projects explore human reaction and intuition as they relate to nature, created the work. Motion sensors and 3-D tracking cameras stop the flow of water whenever a human body is detected, imbuing the entire event with a divine...