What is the hail symbol?

The weather phenomenon symbol "△" indicates hail.

Hail is formed in cumulonimbus clouds formed by 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 its upward movement, it will absorb small ice particles or water droplets around it, and continue to increase until it falls due to the increase in weight. When it drops to a higher temperature zone, its surface will melt into water.

At the same time, it will also absorb small water droplets around it. At this time, if it is lifted by a strong updraft, it will condense into ice particles and continue to condense and grow until it falls due to its own weight. If it doesn't melt into water when it falls to the ground, it will still be solid ice particles or hail.

Main categories:

According to the maximum hail (general hail) diameter, hail accumulation time and hail accumulation thickness in a hail process, the hail is divided into three grades.

1, light hail: the diameter of most hail is less than 0.5cm, the cumulative hail falling time is less than10min, and the hail thickness in the area is less than 2cm.

2. Moderate hail: The diameter of most hail is 0.5~2.0 cm, the cumulative hail falling time is 10~30 minutes, and the hail thickness is 2~5 cm.

3. Heavy Hail: Most hailstones have a diameter greater than 2.0 cm, the cumulative hail time is greater than 30 minutes, and the hail thickness is greater than 5 cm.