Chemical Composition and Source Characterization of Hailstones in Dhaka, Bangladesh

A comprehensive analysis on the chemical composition and source apportionment of hailstone samples were conducted in Dhaka, Bangladesh. pH, electrical conductivity (EC), total dissolved solids (TDS), water soluble ions (Na+, K+, Ca2+, Mg2+, Cl-, SO42-, NO3-, HCO3-) and trace metals (Zn, Fe, Cu, Mn) of hailstone were determined. The result revealed that the average pH, EC, TDS were 6.95 ± 0.54, 356.3 ± 150.6 μS·cm-1 and 17.5 ± 2.89 mg·L-1, respectively. The water soluble ions followed the order: Ca2+ > Cl-1 > SO42- > HCO3- > Na+ > Mg2+ > K+ > NO3-. The concentrations of trace metals ranged in order with Zn > Fe > Cu, while the concentration of Mn was below detection limit. Sodium adsorption ratio (SAR) was 0.20 ± 0.09 meqL-1 which indicates it is benign to plants and safe for irrigation. The order of neutralization factor (calculated with average concentrations) found in hailstone was NFCa(1.16) > NFMg (0.36) > NFK(0.32) which were originated from earth crust. Notable correlation was found in between soil tracers Ca2+ and Mg2+ (r = 0.87), indicating their common source dust. Enrichment factor analysis revealed that Ca2+, Mg2+ and K+ are mainly from crust, whereas NO3- and SO42- are mainly attributable to anthropogenic origins. Further source contribution analysis revealed that anthropogenic actions accounted for 99.2% of total NO3- and 89.6% of total SO42-, while 99.2% of total Ca2+ and 95% Mg2+ were from crustal source.

Characteristics of Hailstone Disaster and the Risk Zoning in Shijiazhuang

By using the hailstone disaster data,the spatio-temporal distribution characteristics of hailstone in Shijiazhuang,the relationship between the hailstone disaster and the weather system,the hailstone path were analyzed.Moreover,the risk zoning of hailstone disaster in every county(city) of Shijiazhuang was done according to the occurrence frequency of hailstone.The results showed that the spatio-temporal distribution characteristics of hailstone in Shijiazhuang were obvious,and there were 3 main paths.The zones where the paths passed were also the high risk areas of hailstone occurrence.The research provided the scientific guidance for the adjustment of agricultural industrial structure and the defense of hailstone disaster.

Hail Sensing Probes: Feasibility Analysis for Probes to Monitor and Study Hail

This work presents the feasibility study regarding the realization of hail sensing probes for remote sensing and study of hail. The probes are designed as artificial hailstones in order to study both the physical properties of the portion of atmosphere where the formation of hail occurs and the modification of atmospheric conditions while the hailstones are falling to the ground. The basic idea is to realize sensors with a similar fluid-dynamic behavior with respect to hailstones;the density, the weight and the size of the probes are determined. Consequently, the specification of the electronic boards, sensors, and material to realize the probes are studied and presented. The hail sensing probes can be dropped by a plane, or potentially a UAV (Unmanned Aircraft Vehicle), which fly above and through the clouds where the hail formation occurs. During their falling to the ground, the sensors installed on the probe measure directly different parameters such as humidity, temperature, pressure, acceleration. All data are sent to a receiver located on the ground. The study of the sampling frequency of each sensor is presented, together with the analysis of the propagation channel, in order to assure a robust communication link between probes and the ground receiver. The energy balance is also computed. The work demonstrates that a set of this kind of disposable sensors can be realized. They can be used for efficient monitoring operations and studies of hail formation dynamics and conditions, thus increasing the set of instruments for the monitoring and remote sensing of hail.

Analysis on the Formation Reason of A Rare Big Hailstone Weather in Nantong City

By using the ground and high-altitude observation data,NCEP 6 h reanalysis data and CINRAD/SA radar observation data,the circulation situation,the atmospheric stability degree and the radar echo characteristics of a strong convection weather which occurred in Nantong area of Jiangsu Province on June 14 in 2009 were analyzed.The results showed that the hailstone happened in the large scale background of coastal trough rear which was established by the northeast low vortex.The warm air in the middle-low layer was covered with the cold air in 500 hPa,which provided the favorable condition for the occurrence of strong convection weather which included the hailstone,the thunderstorm,the strong wind and so on.Seen from the analysis on the radar echo,the windstorm which induced this strong convective weather had the characteristics of super monomer windstorm.In the northwest and the southeast,there were 2 obvious outflow boundaries and the overhanging structure characteristics.The strong vertical shear and the suitable frozen layer height in the middle-low layer of troposphere were also favorable to fall the hailstone.

Analysis on the Unstable Trigger Mechanism of A Rare Strong Convection Weather in North-central Fujian Province

By using NCEP reanalysis data,the formation reason of a disaster weather process which happened in Fujian Province on April 1,2007 was analyzed. The results showed that this strong convection weather process was caused by the development of convective thunderstorm monomer in the warm zone of jet stream which was in front of ground front at afternoon. The invasion of cold advection in the middle-high layer had the major trigger effects on this strong convection weather occurrence. The tilt development of vorticity was easy to appear in θse tilted frontal zone,which made a large amount of latent heat release exist in the middle layer of troposphere. Meanwhile,it favored the potential vorticity in the middle layer to download. Thus,it made the important contributions to the development,maintenance of low-altitude vorticity in the strong convection zone and favored the development,maintenance of thunderstorm. In the middle-low layer of troposphere where the strong convection happened,the distribution of meso-scale wave train which was similar to the gravity wave appeared. Meanwhile,it also reflected the wave characteristics which the ascending motion alternated with the descending motion in the divergence. The westerly disturbance in the middle-low layer of troposphere,the southerly disturbance in the low altitude and the middle-upper layer of troposphere made the important contributions to the strong convection weather. The easterlies disturbance and the divergence effect in the tropopause strengthened the development of vertical motion. The strong vertical wind shear was the favorable condition of strong convection weather occurrence.

Analysis on A Rare Hailstone Process in Early Spring in Linyi Area

By comprehensively using the data which included MICAPS weather chart,Doppler radar data,the numerical forecast and so on,the weather background,the physical mechanism of occurrence and the meso-micro scale characteristics of weather systems in a rare early spring local hailstone process which happened on February 28,2010 in Linyi area were analyzed in detail.The occurrence laws and characteristics of sudden disastrous weather process were found,which accumulated the experience for later forecast and early warning work.