Flying with the clouds

Aircraft cloud detection has become a basic method to determine the characteristics of cloud particle concentrations, liquid water content, and particle spectrum distributions. The airborne Ka-band cloud radar is able to observe the macrostructure of cloud particle characteristics in precipitating clouds during the process of the aircraft penetrating clouds.

In view of this, the Beijing Weather Modification Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, and other units, used aircraft detection data collected in Baoding on 5 August 2018, combined with airborne Ka-band cloud radar, to study the microphysical characteristics of cumulus cloud. The results have recently been published in Atmospheric and Oceanic Science Letters.

According to their findings, in the high liquid-water-content regions above 1500 m, the cloud droplet concentration varied little, the aerosol number concentration decreased, and the cloud droplet average diameter as well as the aerosol effective radius increased slightly.

"All clouds we studied were pure liquid-phase clouds and dominated by spherical particles. Strong updrafts in the cumulus cloud increased the peak radius and cloud droplet concentration, and broadened the cloud droplet spectrum; and lower air temperature was favorable for particle condensational growth and produced larger droplets," explains Dr Lei Wei, from the Beijing Weather Modification Center.

Due to the strong updrafts, the aircraft's ability to detect cumulus clouds is limited.

"If the aircraft can detect cumulus clouds in the vigorous development stage of convection, it is a scientific problem worthy of further discussing the physical characteristics of cumulus clouds," concludes Dr Wei.

Research Report: "Microphysical characteristics of precipitating cumulus cloud based on airborne Ka-band cloud radar and droplet measurements"