The world's largest rain simulation system

Heavy rain in a short period of time, such as rain after a storm, can lead to serious problems. Scientists at NIED* use rainfall simulation systems to study and hopefully prevent.

The world's largest rain simulation system is actually a giant warehouse equipped with 550 spray elephants mounted on the roof. These nozzles have four holes of different diameters, which affect how quickly the raindrops fall.

The system allows scientists to control rain intensity from 15mm per hour to 300mm per hour. In fact, the heaviest amount of rain ever measured in one hour occurred on June 22, 1947, when 305mm of rain fell on the town of Holt, Missouri.

Scientists use the system for research and landslide prevention, testing how drones fly in rainy and windy conditions.

In addition, this artificial rain system is also used to test self-driving cars. Based on the data collected, engineers can improve the hardware and software to help the vehicle detect many different objects. The two main ways that self-driving cars detect other cars, traffic lights and pedestrians are using cameras or Lidar laser sensors. With both, rain can reduce visibility and accuracy. So testing them in a repeatable environment helps engineers discover solutions to this weather challenge.