Precipitation
The amount of precipitation that falls on the ground during rain, hail or snow is given in millimeters of liquid water falling to the earth’s surface.
A rain gauge in the form of a container harvest rainwater. After it fills up, the water level is measured in millimeters and this value indicates the amount of precipitation. It therefore reflects the height of the water level that fell on the earth’s surface in a certain period of time (hour, day, month, year).
If a 1 millimeter of rain falls on 1 square meter of the ground, this is 1 liter of water per square meter.
The average precipitation in the Czech Republic is 450 mm per year, in the Liberec region the annual precipitation average ranges from 600 to 900 mm. Compared to the national precipitation average, the Liberec represents an above-average region in terms of precipitation.
Average precipitation totals depending on the type of rain:
- permanent rain: 1 – 5 mm per hour,
- heavy rain 20 mm per hour,
- extreme torrential rains even 100 mm per hour.
Tasks
- How long will it take to fill the barrel near the house with water if a permanent rain of 7 mm per hour falls on the roof and the roof area is 4 m2?
The total precipitation in 2020 in the Liberec Region was 893 mm (assuming that the snow after melting transforms to water without loss). Rainwater tanks are produced with volumes of 1000 l, 3000 l, 5000 l and 10,000 l. How big a tank should I buy to fit all the precipitation that falls on the roof of a family house with an area of 130 m2 in a year? Estimate the result first.