As part of the home dashboard I am developing, I get information about incoming rain. It is given in mm/min.
Is there a consensus on the precipitation rate that is called "light rain", or "heavy rain"? (I would like, if this is possible, to use some standardized naming)
If there was a worldwide standard, then WMO would have imposed it to its members. Here are the definitions in the American (NOAA/NWS) standard
(summarized at NJWeatherScan, initially from manuals like this one (PDF page 66, page label 58):
Light rain: falling rate of less than 2.54 mm/h. This would be < 0.042 mm/min.
Moderate rain: falling rate of more than 2.8 mm/h, but less than 7.6 mm/h. This would be 0.042 mm/min - 0.127 mm/min.
Heavy rain: falling rate of more than 7.6 mm/h. This would be > 0.127 mm/min.
So clearly different standards compared to the DWD answer (note: 1 l/m² is equivalent to 1mm). Nowadays, automated weather stations use rain gauges with sensors, so a modern station with the computer inside has a clear and accurate computation of rain/snow falling rates. But there is no universal standards.
The German Weather Service (Deutscher Wetterdienst, DWD) provides the following definitions:
Heavy rain is defined as large amounts of precipitation during a fixed period of time. [...]
The DWD issues warnings of heavy rain using three categories:
- heavy rain: 15 to 25 l/m² within 1 hour or 20 to 35 l/m² within 6 hours
- severly heavy rain: 25 to 40 l/m² within 1 hour or 35 to 60 l/m² within 6 hour
- extremely heavy rain: above 40 l/m² within 1 hour or above 60 l/m² within 6 hour
Source: https://www.dwd.de/DE/service/lexikon/begriffe/S/Starkregen.html and https://www.dwd.de/DE/wetter/warnungen_aktuell/kriterien/warnkriterien.html?nn=508722#doc453962bodyText3, translation my own.
Heavy rain is distinct from constant rain by the period of time, over which the rain falls, as well as the total amount of rain per m². Still, heavy rain events may be part of constant rain periods.
