A yellow or orange warning of severe weather was issued in Spain 12. Why are there color grades for warnings?

With the approach of 20021new year, the yellow or orange warning signal will be issued in Spain 12 for severe weather such as snowfall, cold wave and strong wind. Heavy snowfall warnings have been issued in most provinces in central and northern Spain, and orange warnings have been issued in asturias and Cantabria. The thickness of snow may reach 5 to 20 cm, and some mountainous areas in the north have issued avalanche warnings. It is expected that there will be windy weather in most coastal areas of the country, and the highest wind force can reach more than 7. At the same time, the temperature in the whole country, including Iberian Peninsula and Balearic Islands, will generally drop sharply, and frost is expected to appear in most inland areas.

The official name of these colored icons is weather warning signal. Usually, they have four color levels, blue, yellow, orange and red. The severity of these color icons increases in turn, indicating general, serious, serious and particularly serious. Blue is the lowest level warning, and red is the highest level warning.

Blizzard blue warning signal, 12 hours, the snowfall will reach more than 4 mm, or it has reached more than 4 mm and the snowfall continues, which may affect traffic or agriculture and animal husbandry; Typhoon blue warning signal, which may or may have been affected by tropical cyclones within 24 hours, the average coastal or land wind force is above 6, or the gust is above 8 and may continue; Thunderstorm and gale blue warning signal 1 6 hours may be affected by thunderstorm and gale, with average wind speed above 6 or gust above 7 accompanied by lightning; Or have been affected by thunderstorms and strong winds, with an average wind speed of 6-7, or gusts above 7-8 accompanied by lightning, and may continue; Blue rainstorm warning signal, 12 hours, the rainfall will reach more than 50 mm, or it may continue to rain. Blue frost warning signal, the minimum ground temperature will drop below 0℃ within 48 hours, which will have an impact on agriculture, or it will have an impact on agriculture and may continue.

In yellow rainstorm warning signal, the rainfall will reach more than 50 mm within 6 hours, or it has reached more than 50 mm, and the rainfall may continue; Blizzard yellow warning signal, 12 hours of snowfall will reach more than 6 mm, or has reached more than 6 mm, and snowfall continues, which may have an impact on transportation or agriculture. Ozone yellow warning signal, the average hourly concentration in the next 4 hours may be high; Yellow warning signal of forest fire danger, moderate danger, combustible materials in the forest are easy to burn, and forest fires are easy to occur; Snow disaster yellow warning signal, 12 hours of snowfall may affect traffic or agriculture; Yellow warning signal of smog, smog with visibility less than 3,000 meters may appear within 12 hours, or smog with visibility less than 3,000 meters has already appeared and may continue. The typhoon yellow warning signal may be or has been affected by tropical cyclones within 24 hours, and the average wind force along the coast or land is above 8, or the gust is above 10 and may continue.