| Precipitation | Totality of water particles, liquid or solid, that fall down on the earth’s surface (rain, snow, graupel, hail etc.) |
| Dew Point | Indicates the temperature, where the saturation limit is reached – under cooling down of the air – and where dewing starts. |
| Evaporation | The loss of a certain water quantity, caused by a change of its aggregate state into gaseousness, under temperature influence. |
| Precipitation Quantity | The totality of the fallen liquid or solid precipitation. Indicated in mm, i.e. 1 mm of precipitation = 1 litre per square meter. |
| Precipitation Meter | Generally for a precipitation collecting instrument, the collected quantity of which is measured by means of a measuring receptacle. |
| Precipitation Transmitter | Generally for a precipitation measuring instrument with electrical output. Here, an impulse is delivered for a defined precipitation quantity as output value. |
| Precipitation Recorder | Generally for a precipitation measuring Instrument with mechanical recording of the collected precipitation quantity. |
| Snow Cross | Inset for precipitation meters. Avoids losses of snow in the precipitation funnel due to wind vorticities. |
| Rain | Water drops with a diameter of > 0,5 mm, falling down from the atmosphere |
| Drizzle | Water drops with a diameter of < 0,5 mm, falling down from the atmosphere. |
| Hail | Balls of ice with a diameter of approx. > 5 mm, falling down from the atmosphere. |
| Snow | Down-falling snow crystals, single or sticking together. |
| Precipitation Intensity | The fallen precipitation quantity within a certain time period. (e.g. mm/min) |
| Droplet | A nozzle where the liquid precipitation is passed through, and dripped off in a defined drop size. This procedure achieves a high resolution for the precipitation measurement ( e.g. 0,005 mm). |
| Tipping Bucket | The collected liquid precipitation is led into a tipping bucket which tips over at a certain weight. The tipping over corresponds to a defined precipitation quantity (e.g. > 0,1 mm). |
| Evaporation Calculation | Mathematical calculation of the evaporation with different parameters: |
| acc. to Haude | Day’s value of evaporation from temperature and rel. humidity Hourly value of evaporation from temperature, rel. humidity, wind velocity and radiation. |
| acc. to Wendling | Day’s value of the reference evaporation from temperature, rel. humidity, wind velocity and radiation. |
| acc. to Penman-Monteith | Day’s value of evaporation above water from wind velocity, water surface temperature, rel. air humidity and air temperature. |
| acc. to Richter | |
| Guidelines | |
| VDI 3786, Part 7 | Meteorological measurements, precipitation |
| DIN 4049, Part 101 | Hydrology, terms for precipitation and snow cover |
