Classification standard of rainfall grade

Light rain: 1d (or 24h) rainfall is less than 10mm.

Moderate rain: 1d (or 24h) rainfall 10 ~ 25mm.

Rainstorm: 1d (or 24h) rainfall is 25 ~ 50mm.

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

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

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

Light snow: the snowfall process in which the snowfall is less than 1.0mm within 12 hours (equivalent to melting rainfall, the same below) or less than 2.5mm within 24 hours.

Medium snow: 12 hour snowfall1.0 ~ 3.0mm, or 24-hour snowfall of 2.5 ~ 5.0mm or snow depth of 3cm.

Heavy snow: the snowfall process in which the snowfall is 3.0 ~ 6.0mm in 12 hour or 5.0 ~10.0mm in 24 hours or the snow depth reaches 5cm.

Blizzard: A snowfall process in which the snowfall is more than 6.0 mm within 12 hours or more than 10.0 mm within 24 hours or the snow depth reaches 8 cm.

Heavy snowstorm: the snowfall is more than 12.0 mm in12 hours or more than 20.0mm in 24 hours or the snow depth reaches 16CM.

Extraordinary snowstorm:/kloc-the snowfall in 0/2 hour is more than 24.0mm, or the snowfall in 24 hours is more than 30.0mm or the snow depth reaches 32cm.

Rainfall grading standards will consider the following factors:

1. Rainfall: According to different regions and uses, the classification criteria of rainfall levels may be different. Generally speaking, rainfall can be divided into light rain, moderate rain, heavy rain and rainstorm levels. The specific division standard can be determined according to historical rainfall data and actual situation.

2. Rainfall duration: In addition to rainfall, rainfall duration is also an important consideration in classifying rainfall levels. For example, a long light rain may cause floods, and a short heavy rain may cause flash floods.

3. Geographical environment: In different geographical environments, the criteria for classifying rainfall levels will be different. For example, mountainous areas may be more tolerant of heavy rain, while plain areas may have a greater impact on the same rainfall.

4. Impact degree: The classification of rainfall grade also needs to consider the impact degree of rainfall on human activities and natural environment. For example, rainfall has different effects on agriculture, transportation and urban drainage system. Therefore, these factors need to be considered comprehensively in the division standard.

The influencing factors and application scope of rainfall classification are important topics related to meteorology and water resources management. The factors affecting rainfall classification include rainfall, rainfall frequency, rainfall duration and rainfall intensity. Comprehensive evaluation of these factors is helpful to understand the characteristics and trends of rainfall and provide scientific basis for water resources planning, irrigation decision-making, flood control and disaster reduction. In addition, rainfall classification has a wide range of applications, covering agriculture, urban planning, ecological environment protection and other fields. Through the classification and analysis of rainfall grades, we can better understand the impact of rainfall on different fields, so as to take corresponding measures to cope with and adapt to the challenges of climate change and water resources management.

To sum up, the influencing factors and application scope of rainfall classification is an important topic involving meteorology and water resources management.

Legal basis:

Release the Interim Measures for the Administration of Weather Forecast

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The state implements a unified release system for publicly released weather forecasts and severe weather warnings. Meteorological offices and stations at all levels under the jurisdiction of the State Meteorological Administration are responsible for the release. The Central Meteorological Observatory and meteorological stations below all levels are respectively responsible for issuing weather forecasts and severe weather warnings within their respective responsibilities; The Central Meteorological Observatory and coastal meteorological stations at all levels are also responsible for issuing weather forecasts and severe weather warnings in the sea areas under their jurisdiction.