Abstract:

Hail is one of the most important destructive weather phenomena in Ningxia Province,China.Its circulation background and spatiotemporal distribution characteristics have been carefully studied by many researchers,but the research on hail with the newest generation of detection equipment is not very clear.This study addressed this gap by examining hail events with measurements of instantaneous precipitation intensity,total number of precipitation particles,cumulative precipitation,visibility,and radar reflectivity that were obtained using a DSG5 laser raindrop spectrometer.The precipitation and microphysical characteristics of hail falling during severe convective weather in the Liupan Mountain area of Ningxia Province on the night of July 14,2017,were systematically analyzed.The results showed as follows: (1) during the hail process,the microphysical characteristics of the precipitation particles increased significantly relative to the baseline.In particular,the number density and mean kinetic energy flux increased to 6.3 and 13 times more than their initial values,respectively.(2) In the early hailing stage,large hail particles grew faster than did smaller particles.However,with the release of energy,convection weakened and hailstones of smaller size increased rapidly.(3) Our data showed that a gammatype distribution was most suitable for fitting the particle distribution characteristics before and after the hail process.(4) Finally,we found that particle velocity during the hail falling process was well fitted by using the particle falling velocity formula V=aD^b(R²≥0.98).Fitted to our data,the constant a ranged from 4.55 to 5.02,while b varied from 0.53 to 0.59.

Key words: Liupan Mountain')">

Liupan Mountain, hail cloud, hail particle size distribution, microphysical characteristics