A detailed 3-D hail cloud numerical model and parameterization of mierophysieal processes were described in Part Ⅰ(Hong 1999)of this study.In this part,a hail cloud occurring in Xunyi area.Shaanxi Province on July 8,...A detailed 3-D hail cloud numerical model and parameterization of mierophysieal processes were described in Part Ⅰ(Hong 1999)of this study.In this part,a hail cloud occurring in Xunyi area.Shaanxi Province on July 8,1997 is simulated by the model to analyze mechanisms of hail formation and hail suppression with seeding.The results show that 97% of hail embryos are frozen drops.The seeding experiments with AgI in terms of heights show that if the seeding is made before hail formation,the optimum seeding position is located in the maximum updraft area and its center,i.e.,AgI is seeded in the zone with high water content to be coordinated with maximum zone of the updraft.The seeding makes concentrations of graupel and frozen drop increase and their average mass or size decrease,so that the proportion of conversion from graupel and frozen drop into hail descends greatly,and the mass and concentration of hailstone are decreased to achieve our purpose for hail suppression.展开更多
A case of hailstorm process occurring on 24 June 2006 in northwestern China was studied using satellite retrieval methodology. The particle effective radius (re) in the cloud tops was calculated by the reflectance in ...A case of hailstorm process occurring on 24 June 2006 in northwestern China was studied using satellite retrieval methodology. The particle effective radius (re) in the cloud tops was calculated by the reflectance in the 3.7 μm channel, and cloud-top microphysical properties were vividly represented using the RGB visual multispectral classification scheme. The microphysical zones of clouds and the processes of hail formation and develop-ment are inferred using the relations of cloud-top temperature (T) versus re for the tops of convective clouds. The results show that particle effective radius was smaller near the cloud base of hailstorm. There was a deep zone of diffusional droplet growth at the low level where the particles grew slowly with height, and there existed an evident area of small ice particles in the cloud top, suggesting the existence of a strong updraft in the clouds. The low glaciated temperature indicated a great depth from the cloud base to the glaciation height, which provided a deep layer of supercooled water for hail growth.展开更多
Based on routine weather charts, numerical predication products and satellite cloud images, the causes of an infrequent regional hail weather process occurred in east of Gansu on Aug. 2, 2006 were diagnosed and analyz...Based on routine weather charts, numerical predication products and satellite cloud images, the causes of an infrequent regional hail weather process occurred in east of Gansu on Aug. 2, 2006 were diagnosed and analyzed. The results showed that the hail weather process occurred at the abnormal large-scale circulation leading the system to west. When the cold trough, which was separated by the north cold vortex, moved southward through Hetao and then intersected with 300 hPa jet stream and the surface cold front, that led to the strong convection. There were strong upward motion and unstable stratification in hail area, three MCS in satellite cloud, and a character of formed arch shape echo on radar echo charts.展开更多
Based on the conventional observation data,satellite,radar,automatic observation and other refined monitoring data,the severe hail weather in Hohhot City on July 29,2015 was analyzed at multiple scales.The results sho...Based on the conventional observation data,satellite,radar,automatic observation and other refined monitoring data,the severe hail weather in Hohhot City on July 29,2015 was analyzed at multiple scales.The results showed that from the perspective of synoptic-scale system,high-altitude cold air invaded Mongol shortwave trough,and the North China small high pressure and the subtropical high formed a warm shear line;the surface convergence line triggered severe convection weather.Unstable vertical structure,continuous increase of low-level humidity,more drier of high altitudes and the wind direction shear at 180° triggered hailstorm and lightning weather in Hohhot.α-scale convective cloud clusters were maintained in Hohhot,and the ground "herringbone" shear line oscillated violently between the north and the south.Strong lightning and big hails appeared on the ground.The "herringbone" shear line lifted slowly to the north,and there was short-time heavy precipitation on the ground.Radar products showed "bow echo",and the echo had a hanging structure;a mesoscale cyclone was formed 3 km away from the ground.On the radar wind profile,it can be seen that low-layer warm advection and strong wind shear triggered strong hailstorm in Hohhot.The disappearance of low- level warm advection and the maintenance of strong vertical shear of wind produced short-time heavy precipitation.There was a small difference between short-time heavy precipitation and hail in echo top height,but the coverage was significantly reduced.In Hohhot City,vertically integrated liquid water content quickly increased during the hail,and decreased during the short-time heavy precipitation.展开更多
Cloud seeding is a method of artificially causing clouds to produce precipitation (降水) in the form of rain or snow.Cloud seeding has also been used in attempts to modify the severity of hail slorms and hurricanes.Th...Cloud seeding is a method of artificially causing clouds to produce precipitation (降水) in the form of rain or snow.Cloud seeding has also been used in attempts to modify the severity of hail slorms and hurricanes.The effectiveness of cloud seeding remains controversial,but it continues to be used in some regions to try lo展开更多
文摘A detailed 3-D hail cloud numerical model and parameterization of mierophysieal processes were described in Part Ⅰ(Hong 1999)of this study.In this part,a hail cloud occurring in Xunyi area.Shaanxi Province on July 8,1997 is simulated by the model to analyze mechanisms of hail formation and hail suppression with seeding.The results show that 97% of hail embryos are frozen drops.The seeding experiments with AgI in terms of heights show that if the seeding is made before hail formation,the optimum seeding position is located in the maximum updraft area and its center,i.e.,AgI is seeded in the zone with high water content to be coordinated with maximum zone of the updraft.The seeding makes concentrations of graupel and frozen drop increase and their average mass or size decrease,so that the proportion of conversion from graupel and frozen drop into hail descends greatly,and the mass and concentration of hailstone are decreased to achieve our purpose for hail suppression.
基金supported jointly by Chinese Ministry of Science and Technology (Grant 2005DIB3J099)Science Foundation of Shaanxi Province (Grant 2007D11)
文摘A case of hailstorm process occurring on 24 June 2006 in northwestern China was studied using satellite retrieval methodology. The particle effective radius (re) in the cloud tops was calculated by the reflectance in the 3.7 μm channel, and cloud-top microphysical properties were vividly represented using the RGB visual multispectral classification scheme. The microphysical zones of clouds and the processes of hail formation and develop-ment are inferred using the relations of cloud-top temperature (T) versus re for the tops of convective clouds. The results show that particle effective radius was smaller near the cloud base of hailstorm. There was a deep zone of diffusional droplet growth at the low level where the particles grew slowly with height, and there existed an evident area of small ice particles in the cloud top, suggesting the existence of a strong updraft in the clouds. The low glaciated temperature indicated a great depth from the cloud base to the glaciation height, which provided a deep layer of supercooled water for hail growth.
基金Supported by Meteorological Research Program of Gansu Province:Thunder and Lightning Monitor Based on New Generation Weather Radar and LD-II Thunder and Lightning Locator Prediction Services System Research of Pingliang City
文摘Based on routine weather charts, numerical predication products and satellite cloud images, the causes of an infrequent regional hail weather process occurred in east of Gansu on Aug. 2, 2006 were diagnosed and analyzed. The results showed that the hail weather process occurred at the abnormal large-scale circulation leading the system to west. When the cold trough, which was separated by the north cold vortex, moved southward through Hetao and then intersected with 300 hPa jet stream and the surface cold front, that led to the strong convection. There were strong upward motion and unstable stratification in hail area, three MCS in satellite cloud, and a character of formed arch shape echo on radar echo charts.
文摘Based on the conventional observation data,satellite,radar,automatic observation and other refined monitoring data,the severe hail weather in Hohhot City on July 29,2015 was analyzed at multiple scales.The results showed that from the perspective of synoptic-scale system,high-altitude cold air invaded Mongol shortwave trough,and the North China small high pressure and the subtropical high formed a warm shear line;the surface convergence line triggered severe convection weather.Unstable vertical structure,continuous increase of low-level humidity,more drier of high altitudes and the wind direction shear at 180° triggered hailstorm and lightning weather in Hohhot.α-scale convective cloud clusters were maintained in Hohhot,and the ground "herringbone" shear line oscillated violently between the north and the south.Strong lightning and big hails appeared on the ground.The "herringbone" shear line lifted slowly to the north,and there was short-time heavy precipitation on the ground.Radar products showed "bow echo",and the echo had a hanging structure;a mesoscale cyclone was formed 3 km away from the ground.On the radar wind profile,it can be seen that low-layer warm advection and strong wind shear triggered strong hailstorm in Hohhot.The disappearance of low- level warm advection and the maintenance of strong vertical shear of wind produced short-time heavy precipitation.There was a small difference between short-time heavy precipitation and hail in echo top height,but the coverage was significantly reduced.In Hohhot City,vertically integrated liquid water content quickly increased during the hail,and decreased during the short-time heavy precipitation.
文摘Cloud seeding is a method of artificially causing clouds to produce precipitation (降水) in the form of rain or snow.Cloud seeding has also been used in attempts to modify the severity of hail slorms and hurricanes.The effectiveness of cloud seeding remains controversial,but it continues to be used in some regions to try lo
