Olympics Weather Forecasting Medium Medium A project to improve weather forecasting during the Olympics has begun, with the installation in Sydney of a device to measure the size of raindrops. The distrometer, about the size of a coffee cup, is crucial to the calibration of the Bureau's radars at Kurnell and in Wollongong, which cover Sydney. It measures the momentum of raindrops as they fall on it.
Radars work by transmitting and receiving microwaves.
If the microwaves hit an obstacle like rain they are reflected and detected by the radar antenna. The time between the transmission and echo reveals the location of the rainstorm, and enables meteorologists to work out where the storm is heading. The intensity of the echo reveals the severity of the storm. But intensity is also influenced by the raindrop size distribution, which depends on the type of storm and geography. The distrometer measures raindrops from 0.25 mm to 5 mm in diameter.