A Strong Thunderstorm with Snow Grains Has Just Left Its Mark on the Gomance Terrain; Snežnika/Mount Snežnik Area, Karst-Dinaric Region, Slovenija (Hrvatska State Border)
15-April-2023
Cold air at high altitudes and overheating of the ground by the (previous) sun generated intense thunderstorm activity in the cores of which a phenomenon was formed which many, by approximation, mistake for hail.
The formation of granular snow/snow grains (or white hail) is all in all similar to that of hail but occurs in clouds mainly composed of ice crystals and not water droplets as typical in spring with thermal 0°C at relatively low altitude.
The updrafts of the "hot part" of the Thunderstorm, which feed the cell, carry/drag humidity and ice crystals (droplets in the case of hail) upwards which compact to form little balls, grains or rice of snow covered with a thin film of black ice, which then fall by gravity from the cold part of the storm (downdraft) where rainfall is concentrated.
What is evident for those who have witnessed both phenomena (the "pure" hail here occurs only in summer in case of heavy thunderstorm) it is the specific weight of the individual snow grain and hailstone, the former decidedly lighter and slower in falling, the latter much harder, compact and faster (and much less white), which can cause serious damage as opposed to the harmless white hail.
Naturally, like everything in meteorology, the clear classification of the phenomena is only formal and concerns the 2 extremes, in reality there is a considerable variety of nuances in the relationship between water and snow to compose the solid precipitations described.
A Strong Thunderstorm with Snow Grains Has Just Left Its Mark on the Gomance Terrain; Snežnika/Mount Snežnik Area, Karst-Dinaric Region, Slovenija (Hrvatska State Border)
15-April-2023
Cold air at high altitudes and overheating of the ground by the (previous) sun generated intense thunderstorm activity in the cores of which a phenomenon was formed which many, by approximation, mistake for hail.
The formation of granular snow/snow grains (or white hail) is all in all similar to that of hail but occurs in clouds mainly composed of ice crystals and not water droplets as typical in spring with thermal 0°C at relatively low altitude.
The updrafts of the "hot part" of the Thunderstorm, which feed the cell, carry/drag humidity and ice crystals (droplets in the case of hail) upwards which compact to form little balls, grains or rice of snow covered with a thin film of black ice, which then fall by gravity from the cold part of the storm (downdraft) where rainfall is concentrated.
What is evident for those who have witnessed both phenomena (the "pure" hail here occurs only in summer in case of heavy thunderstorm) it is the specific weight of the individual snow grain and hailstone, the former decidedly lighter and slower in falling, the latter much harder, compact and faster (and much less white), which can cause serious damage as opposed to the harmless white hail.
Naturally, like everything in meteorology, the clear classification of the phenomena is only formal and concerns the 2 extremes, in reality there is a considerable variety of nuances in the relationship between water and snow to compose the solid precipitations described.