Hail is most common within continental interiors of the mid-latitudes, as hail formation is considerably more likely when the freezing level is below the altitude of 11,000 feet (3,400 m).Movement of dry air into strong thunderstorms over continents can increase the frequency of hail by promoting evaporational cooling which lowers the freezing level of thunderstorm clouds giving hail a larger volume to grow in. Accordingly, hail is less common in the tropics despite a much higher frequency of thunderstorms than in the mid-latitudes because the atmosphere over the tropics tends to be warmer over a much greater altitude. Hail in the tropics occurs mainly at higher elevations.
Hail growth becomes vanishingly small when air temperatures fall below −30 °C (−22 °F) as supercooled water droplets become rare at these temperatures.Around thunderstorms, hail is most likely within the cloud at elevations above 20,000 feet (6,100 m). Between 10,000 feet (3,000 m) and 20,000 feet (6,100 m), 60 percent of hail is still within the thunderstorm, though 40 percent now lies within the clear air under the anvil. Below 10,000 feet (3,000 m), hail is equally distributed in and around a thunderstorm to a distance of 2 nautical miles (3.7 km).
In response to frequent hail disasters
1.Change the types of crops.
According to many years' production experience, it is reasonable to layout properly and try to avoid the hail line and hail nest with planting potato, peanut and sweet potato and some root crops so that the hail cannot play a part.
2.Change cultivated time.
Master the hailstorm period and adjust the sowing time of the crops to avoid the multiple periods of hail.
3.Hail elimination.
By means of high-technology to disperse or remove hails artificially. The hail cloud can be carried out in time by rocket.
4.Reduce losses.
After the occurrence of hail, remove water and debris in the field. If it is possible for affected crops to restore growth, quick-acting chemical can be fertilized to lift temperature, or watering the land to have hails melted as soon as possible. On some seriously affected lands, those crops should be grafted that have a short growth period and can mature early, or some vegetables can be planted to reduce the losses caused by hail.
5.Listen to the forecast.
Listen to the weather forecast, pay attention to weather changes and be ready to hail and lightning. Outdoor pedestrians should immediately come to a safe place away from hail.
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