Based on the hourly precipitation from automatic weather stations, radar data at Xifeng station and radiosonde data at Pingliang station from 2008 to 2018, the temporal and spatial distribution, physical quantities and radar echo characteristics of short-term heavy rainfall in the Loess Plateau of Qingyang were analyzed statistically. The results are as follows: (1) The short-term heavy rainfall was easily to occur in the north and southeast of the Loess Plateau of Qingyang, and the business forecast should focus in Huan county and Zhengning county. (2) The earliest and latest short-term heavy rainfall occurred in mid-April and mid-October in the Loess Plateau of Qingyang from 2008 to 2018, respectively, and it occurred mostly in July and August, the peaks were in mid-July and mid-August. The diurnal variation of short-term heavy rainfall appeared typical double peaks pattern, the major and minor peaks occurred at about 17:00 BST and 09:00 BST, respectively, and the frequency of short-term heavy rainfall with different levels was higher from 16:00 BST to 18:00 BST. (3) The early warning indicators of water vapor condition of short-term heavy rainfall were 700 hPa specific humidity equal to or more than 7 g·kg-1 and temperature dew-point difference equal to or less than 4 ℃ in the Loess Plateau of Qingyang, as to energy condition, CAPE was equal to or more than 100 J·kg-1 and CIN was equal to or less than 120 J·kg-1, and for instability condition, △T7-5 was equal to or more than 15 ℃ and SI was equal to or less than 1 ℃. In addition, the early warning indicators of -20 ℃ and 0 ℃ layers height averaged 8.6 km and 5.1 km, and the thickness of frozen layer averaged 3.4 km. (4) The radar echo intensity of short-term heavy rainfall exceeded 38 dBZ, the height of echo top and the strongest echo center were more than 7.0 km and 3.6 km, respectively, and the VIL was more than 20 kg·m-2, which could be used for early warning indicators of short-term heavy rainfall. Upon inspection, these early warning indicators could provide some useful references for potential forecast and nowcasting of short-term heavy rainfall in the Loess Plateau of Qingyang.

After deducing external trajectory calculation method under non-standard atmospheric conditions for 37 mm anti-aircraft gun, which was widely used in the field of weather modification, the ballistic data in uniform cross wind and range wind field were simulated. The results show that the wind made a great influence on the flight path of projectile. The range wind can change the ballistic range by affecting the size and direction of air resistance. The cross wind can generate a lateral deviation of the trajectory along the wind by affecting the direction of the air resistance. On the same launch elevation angle, with the change of wind speed, the trajectory deviation correction caused by cross wind and the range correction caused by range wind showed a variation law that was similar to arithmetic progression. Through fitting analysis, the relationship among wind speed, elevation and trajectory correction was obtained，which can be used to estimate trajectory correction under arbitrary wind speed in actual operation.