On Nanling Square in Nanling County, Wuhu, Anhui Province, many citizens were struck by lightning. Under what circumstances are people vulnerable to lightning?

Several people were struck by lightning in Nanling Square, Nanling County, Wuhu City, Anhui Province. Two residents of Nanling County told reporters that at around 7: 50, four people were struck by lightning and two died in Nanling Square. The injured were taken to hospital for treatment. Two lightning victims were sent to Nanling County People's Hospital for treatment. One was observed in the emergency department and the other in the ICU. The public security fire department immediately rushed to the scene to deal with the incident. The casualties and the cause of the incident are under investigation and the results will be announced to the public.

Sites with low soil resistivity are prone to charge accumulation, especially wet sites and high water level sites, such as large salt pans, river beds, ponds, weed ponds and metal deposit areas, which are prone to lightning strikes. Places where sudden changes in soil resistivity are vulnerable to lightning, such as rock-soil boundaries, hillsides, rice fields, etc. Shallow groundwater outlet and large mineral spring outlet are easy to land. In rocky mountains or slopes with high soil resistivity, lightning strikes mostly occur at the foot of the mountain. Hillside with low soil or soil resistivity is easy to be struck by lightning at the top of the mountain. From the distribution of landing probability, the number of lightning strikes on the east and south slopes of the mountain is more than that on the north and west slopes of the mountain. The probability of being struck by lightning is higher in mountainous areas than in narrow valleys. In areas near mountains or water, low-lying and humid areas near the water surface are vulnerable to lightning strikes, especially in thunderstorm corridors such as mountain passes, tuyeres or river valleys, which are more vulnerable to lightning strikes in the same wind direction.

Isolated buildings in open areas, high-rise buildings in buildings and particularly humid buildings (such as ice depots and cold storage) are vulnerable to lightning strikes; Communication towers, receiving antennas, overhead power lines, power line corners and hubs where railway lines are concentrated are all vulnerable to lightning strikes. Depending on the inclination of the roof, buildings will be hit in different places. The flat roof or the slope does not exceed one tenth of the roof, and the parts vulnerable to lightning are cornices, retaining walls and eaves; For roofs with a slope greater than110 and less than 1/2, the parts vulnerable to lightning strike are corners, roofs, eaves, and the roof length is less than 30m, and the lightning strike point is easy to occur at gables. Roofs with slopes greater than 1/2 are vulnerable to lightning strikes at corners, roofs and eaves. The higher the slope, the lower the lightning strike rate of the roof. When the slope is greater than 4/5, the eaves will not be struck by lightning.