Color classification of cold wave levels Classification of cold wave warning levels
Introduction: In the cold winter, we often hear words such as cold wave warnings, including relevant meteorological departments that will also issue corresponding cold wave warnings based on the weather. So, what are the colors of the cold wave levels? What are the criteria for classifying cold wave warning levels? Let’s take a look below.
The colors of cold wave levels are blue, yellow, orange, and red. This type of disaster warning signal is generally divided into four levels: Level IV (general), Level III (relative) Severe), Level II (serious), Level I (extremely severe). The cold wave warning signal is divided into four levels: Level IV (general), Level III (serious), Level II (severe), Level I (especially severe). Serious), marked with blue, yellow, orange, and red Chinese and English icons respectively.
1. Cold wave blue warning signal
Standard: the minimum temperature will drop by more than 8℃ within 48 hours, the minimum temperature will be less than or equal to 4℃, and the average wind force on land can reach level 5 or above; Or it has dropped by more than 8℃, the minimum temperature is less than or equal to 4℃, and the average wind speed has reached level 5 or above, and may continue. or It has dropped by more than 10℃, the minimum temperature is less than or equal to 4℃, and the average wind speed has reached level 6 or above, and may continue. or It has dropped by more than 12°C, the lowest temperature is less than or equal to 0°C, and the average wind speed has reached level 6 or above, and may continue. or It has dropped by more than 16°C, the lowest temperature is less than or equal to 0°C, and the average wind speed has reached level 6 or above, and may continue.
The dangers of cold wave:
1. Cold wave and strong wind
Cold wave and strong wind are windy weather caused by cold wave weather. Cold wave and strong winds cover a wide area. Inner Mongolia, Gansu, Ningxia, northern Shaanxi, northern Shanxi, Hebei, northern Henan, Heilongjiang, Jilin and Liaoning are all areas with frequent cold wave and strong winds in northern China. From the south of the Huaihe River to the South China Sea, Cold wave strong winds can also occur in the central sea area. Cold wave winds are mainly northerly winds, with wind force usually at level 5 to 6. When the cold air is strong or low pressure on the ground develops strongly, the wind force can reach level 7 to 8, and the instantaneous wind force will be stronger.
2. Cold wave freezing damage
An obvious feature of cold wave weather is severe cooling. Low temperature can cause frost damage to crops, freezing of rivers and ports, and traffic interruption disasters, often causing economic losses to industry and agriculture. . Cold wave freezing damage specifically refers to the freezing damage caused by severe cold in winter to overwintering crops. The cold wave weather process is a weather process in which large-scale strong cold air moves southward in high latitudes, causing severe cooling and strong winds in the places it passes. When the temperature drops below 0℃ (freezing point) or remains below 0℃ for a long time, the plants of overwintering crops will freeze and lose all physiological activities, causing the plants to wither or die. Severe low temperatures can also cause livestock diseases. Disease or freezing to death, causing serious meteorological disasters in agriculture and animal husbandry, that is, cold wave freezing damage. Cold wave freezing damage mainly occurs when plant tissues are frozen due to low temperatures below 0℃ (freezing point). Many research results show that the freezing of cell tissues caused by low temperature is the cause of plant death.
3. Cold wave and snow disaster
During the cold wave, the most prominent weather conditions are snowfall (rain), strong winds and severe cooling. Appropriate snow coverage in winter is beneficial to crops overwintering, increasing soil moisture, freezing pest eggs, reducing air pollution, etc. However, cold waves bring excessive snowfall, or even snowstorms for several days or more than ten consecutive days, which can cause disaster. In pastoral areas, due to the "white disaster" caused by cold wave and snowstorm, the pasture is buried deep in the snow, the livestock cannot eat fresh grass, and the supply of hay is not available, resulting in freezing, starvation or illness, and a large number of deaths, which is very harmful to the animal husbandry industry.