What does the rainfall number on the weather forecast mean?
Precipitation
The depth of the water layer that accumulates on the water surface without evaporation, infiltration, or loss is called rainfall (in millimeters). (unit), which can visually represent the amount of rainfall. Currently, commonly used instruments for measuring rainfall include rain gauges and measuring cups. The diameter of the rain gauge is generally 20 cm and contains a funnel and a bottle. The diameter of the measuring cup is 4 cm, and it is used together with the rain gauge. When measuring, pour the rainwater from the rain gauge into the measuring cup, and you can know the amount of rainfall that day based on the scale on the cup.
The China Meteorological Administration stipulates that the rainfall within 24 hours is called daily rainfall. Any daily rainfall below 10 mm is called light rain, 10.0-24.9 mm is moderate rain, and 25.0-49.9 mm is heavy rain. , heavy rains are 50.0-99.9 mm, heavy rainstorms are 100.0-250.0 mm, and those exceeding 250.0 mm are called extremely heavy rains.
Due to the vast territory of our country, a few regions have other regulations based on the specific conditions of their provinces. For example, in rainy Guangdong, a daily rainfall of more than 80 mm is called a heavy rain; in Shaanxi's Yan'an area with little rain, a daily rainfall of more than 30 mm is called a heavy rain.
If you don’t have a rain gauge on hand, don’t worry. You can make one yourself using some common utensils, and the effect is quite good. Take a disposable plastic or paper bowl with a diameter of 20 cm (you can choose an instant noodle bowl of appropriate size), drill a small hole slightly larger than a corn kernel in the bottom, and then place the bowl on an uncovered jar . There is a glass bottle inside the jar, and the mouth of the bottle is connected to the small hole in the bottom of the bowl. The simple rain gauge is ready. After the simple rain gauge is completed, it can be placed 70 cm above the ground (the distance between the mouth of the tube and the ground) to receive rainwater.
After the rain stops, use a scale to weigh the water in the bottle. 30 grams of water is equivalent to 1 mm of rainfall