Classification of rainstorm grades

The classification of rainstorm levels, rain is actually good or bad, depending on the situation, but rainstorm is definitely not a good thing, and rainstorm is also divided into certain levels. The greater the grade, the greater the harm. The following is the classification of rainstorm grades in China. Let's have a look.

Classification of rainstorm grades 1 Rainstorm grades are divided into: rainstorm, heavy rainstorm and extremely heavy rainstorm, as follows:

Rainstorm: 1d (or 24h) rainfall 50 ~ 100mm.

Rainstorm: 1d (or 24h) rainfall 100 ~ 250mm.

Extraordinary rainstorm: 1d (or 24h) rainfall is more than 250mm.

Rainfall is measured by rain gauge or rain gauge, and the unit is millimeter. Daily rainfall observation can be divided into four types: 24 segments (1h), 8 segments (3h), 4 segments (6h) and 1 segment (24h). There are two methods for daily rainfall statistics: 20-20 hours and 08-08 hours. The daily rainfall released by TV and radio programs in China is 08 ~ 08, which represents the rainfall of the previous day.

Extended data

Season and Distribution of Heavy Rain in China

China is a rainy country. Except for some provinces in the northwest, it is almost always heavy rain. Winter rainstorm is limited to the coastal areas of South China, with frequent rainstorm in South China from April to June. From June to July, persistent rainstorms often occur in the middle and lower reaches of the Yangtze River, with long duration, wide range and large amount of rainstorms. July-August is the main rainstorm season in northern provinces, and the rainstorm intensity is very strong. From August to 65438+ 10, the rain belt gradually withdrew southward. After summer and autumn, the typhoon rainstorm in the East China Sea and the South China Sea is very active, and the point rainfall of typhoon rainstorm is often very large.

China has a monsoon climate. From late spring to midsummer, the cold air in the north fought and retreated. Cold and warm air frequently meet, forming a series of heavy rains. The position of the main rain belt in Chinese mainland also moves from south to north with the seasons. South China (Guangdong, Guangxi, Fujian and Taiwan Province) is the region with the most rainstorm in China. April to September is the rainy season.

The second half of June to the first half of July is usually the rainy season in the Yangtze River basin. In late July, the rain belt moved to the north of the Yellow River. After September, the winter wind was established and the rain belt retreated south.

Affected by the summer monsoon, the number of rainstorm days and rainfall distribution in China decrease from southeast to northwest inland, with mountains more than plains. Moreover, the southeast coastal islands and coastal areas have the largest number of rainstorm days, and the farther northwest, the less. In the northwest plateau, there is less than one day of heavy rain on average every year. Mountain slopes in the southeast or east, such as Taihang Mountain, Dabie Mountain, Nanling Mountain and Wuyishan Mountain, are the centers of rainstorm days in these areas.

Classification of rainstorm grades 2 Meteorological departments call it rain and snow precipitation, and precipitation is called precipitation. Precipitation refers to the depth at which liquid and solid (after melting) precipitation falls from the sky to the ground and accumulates on the horizontal plane without evaporation, infiltration and loss. His unit is millimeters. 1mm precipitation refers to the water depth per unit area1mm.

Meteorology uses precipitation to distinguish the intensity of precipitation. It can be divided into: light rain, moderate rain, heavy rain, heavy rain, heavy rain, heavy rain, heavy rain, heavy rain, light snow, medium snow, heavy snow and blizzard.

Light rain: raindrops are clearly visible without floating; The ground does not splash; The water in the depression is slow; The rain on the house is weak, and there is only dripping water on the eaves; 12 hour precipitation is less than 5mm or 24 hour precipitation is less than10mm.

Moderate rain: the rain falls like a line, and the raindrops are not easy to distinguish; Fall heavily and splash; Water accumulated in depression is faster; There is rustling rain on the roof; 12 hour precipitation 5 ~10 ~ 25mm or 24 hour precipitation10 ~ 25mm.

Heavy rain: the rain falls like a downpour, blurred into pieces; The water in the depression is extremely fast; There is rain on the roof; 12 hour precipitation15 ~ 30mm or 24-hour precipitation of 25 ~ 50mm.

Rainstorm: Any rainfall process with precipitation exceeding 50 mm within 24 hours is collectively referred to as rainstorm.

According to the intensity of rainstorm, it can be divided into three types: rainstorm, heavy rainstorm and extremely heavy rainstorm.

Rainstorm: a rainfall process in which the precipitation is 30 ~ 70 mm in 12 hours or 50 ~ 100 mm in 24 hours.

Rainstorm:/kloc-the rainfall process with precipitation of 70 ~ 100~250mm in 0/2 hours or precipitation 100~250mm in 24 hours.

Extraordinary rainstorm: the rainfall process in which the precipitation is greater than140mm in 2 hours or 250mm in 24 hours.

The rainstorm level is divided into 3 1, and the rainstorm is divided into four levels: rainstorm blue warning, rainstorm yellow warning, rainstorm orange warning and rainstorm red warning.

2. Blue rainstorm warning:/kloc-within 0/2 hours, the rainfall will reach more than 50 mm, or it has reached more than 50 mm and the rainfall may continue.

3. Yellow rainstorm warning: within 6 hours, the rainfall will reach more than 50 mm, or it has reached more than 50 mm and the rainfall may continue.

4, rainstorm orange warning: within 3 hours, the rainfall will reach more than 50 mm, or it has reached more than 50 mm and the rainfall may continue.

5. Red rainstorm warning: within 3 hours, the rainfall will reach 100 mm or above, or it has reached 100 mm and the rainfall may continue.

Rainstorm is one of the main meteorological disasters in China. Long-term rainstorm is easy to produce water accumulation or runoff flooding low-lying areas, resulting in floods. According to the statistics of 19xx ~ 19xx, the average flood disaster area in China for many years is 9.424 million hectares, and the affected area of farmland in severe flood years can reach more than130,000 hectares. Rainstorm is a kind of disastrous weather with serious influence.

Continuous rainstorm, heavy rainstorm and extremely heavy rainstorm in a certain area will often lead to flash floods, reservoir dam breaks, rivers flooding, houses being washed away, farmland being flooded, traffic and telecommunications being interrupted, which will bring serious harm to the national economy and people's lives and property. Heavy rain, especially large-scale continuous heavy rain and concentrated heavy rain, not only affects industrial and agricultural production, but also may endanger people's lives and cause serious economic losses.