If it hails, what are the characteristics of clouds?

Hail is often called hail. Hail is formed in convective clouds. Water vapor rises with the airflow and condenses into small water droplets after cooling. If the temperature continues to decrease with the increase of height and reaches below zero degrees Celsius, water droplets will condense into ice particles. In the process of upward movement, it will absorb small ice particles or water droplets around it and grow up until the updraft cannot bear its weight. When it falls to a higher temperature area, its surface will melt into water and absorb the surrounding small water droplets. At this time, if it is lifted by a strong updraft, its surface will condense into ice and snowball again and again until its weight is greater than the buoyancy of the air, that is, it will fall. If it reaches the ground, it is called hail. If it melts into water, it is the rain we usually see.

Hail is a kind of solid precipitation. It is a spherical or conical ice block, which consists of transparent layers and opaque layers alternately. Generally, the diameter is 5 ~ 50 mm, and sometimes it can reach more than 10 cm, which is also called hail or hail block. Hail often destroys crops and threatens the safety of people and animals. This is a serious natural disaster. Many countries with severe hail disasters have carried out artificial hail suppression experiments.

hail

The bigger the hail, the more destructive it is. Hail falls from strong convective cumulonimbus clouds, and the updraft in the clouds is stronger than that in general thunderstorm clouds. Small hailstones grow in convective clouds through several collisions between hailstones and supercooled water droplets, and then fall to the ground when the updraft in the clouds can't support them. Heavy hail is produced in a thunderstorm cloud with strong updraft and rich liquid water. The scope of each hail is very small, usually several meters to several kilometers wide and 20-30 kilometers long, so there is a folk saying that "hail hits a line". Hail mainly occurs in mid-latitude continental areas, usually more in mountainous areas than in plains, and more in inland areas than in coastal areas. Hail in China mostly occurs in spring, summer and autumn, accounting for about 70% of the total from April to July. Southern Gansu, Longdong, Yinshan, Taihang Mountain, western Sichuan and Yunnan Province are serious hail disaster areas.

Hail disaster is a serious meteorological disaster caused by strong convective weather system. Although it appears in a small range and in a short time, it is fierce and strong, and is often accompanied by sudden disastrous weather processes such as strong winds, heavy precipitation and sharp cooling. China is a country with frequent hail disasters. Hail brings huge losses to agriculture, construction, communication, electricity, transportation and people's lives and property every year. According to statistics, the economic losses caused by hail in China reach hundreds of millions or even billions of yuan every year. Therefore, it is necessary for us to understand the temporal and spatial turbulence pattern of hail disaster and the losses caused by hail disaster, so as to better prevent hail disaster and reduce economic losses.