13.  "Present time" sensors

"Real-time" sensors are a new generation of sensors that indicate the main characteristics of hydrometeors.

These sensors detect the presence of precipitating hydrometeors and seek to classify them: drizzle, rain, freezing rain, snow, rain and snow mix, hail, with an indication of their intensity. Some also provide information on visibility (meteorological optical range). All meteorological services are currently interested in these sensors, as they can eliminate the need for human observers to monitor current weather conditions.

The automation of real-time observation required the definitions of certain parameters to be clarified. For example, at what intensity should precipitation be detected? Is a drop falling on the surface of a hand sufficient? Should a sensor be highly sensitive in order to detect a drop, at the risk of providing a...