Quantification of Observed Electrical Effect on the Raindrop Size Distribution in Tropical Clouds

Abstract

In the backdrop of extensive laboratory and theoretical evidence of broadening of the drop size distribution (DSD) of raindrops in the presence of electric field, quantification of the same in observed tropical clouds is lacking. Here this is quantified using the DSD measured by a microrain radar at 2,400‐, 1,200‐, and 600‐m heights from the surface in six strongly electrified and six weakly electrified stratiform rain events together with the DSD of raindrops at the surface measured by a disdrometer for the same cases. The presence/absence of lightning is used to distinguish between strongly and weakly electrified events. The vertical profile of Median Volume Diameter below the melting layer and DSDs at all three heights for strongly electrified events and weakly electrified events are significantly different from each other, consistent with previous laboratory and numerical studies (Rayleigh, 1879; Davis, 1964; Moore et al., 1964, https://doi.org/10.1175/1520-0469(1964)021<0646:GORAMA>2.0.CO;2). Our results indicate that the electric field and surface charge of raindrops can affect the collision‐coalescence process and breakup characteristics of raindrops. Our study suggests that the parameterization of electrical processes in weather/climate models can possibly improve the simulation of tropical rainfall in numerical models as well as a proper representation of DSD will improve the estimation of tropical rainfall in airborne measurements.

A diagnostic study of cloud physics and lightning flash rates in a severe pre‐monsoon thunderstorm over northeast India

“…The underestimation of rainfall in the model for deep convective clouds in the presence of a strong electric field might be related to the underestimation of raindrop size distribution (RDSD) as reported by Mudiar et al . ().…”

Role of Electrical Effects in Intensifying Rainfall Rates in the Tropics

“…The electrical characteristics of the four rain events chosen for the simulation experiments are ascertained by the presence/absence of lightning discharges in the innermost model domain. Lightning data from the World Wide Lightning Location Network (WWLLN) with a detection efficiency of 25%-30% for cloud to ground flashes (CG) (Mudiar et al,2018) and the Maharashtra Lightning Location Network (MLLN) with a detection efficiency of about 90% for CG (Greeshma et al, 2021) are analyzed in this study. Some of the available cloud properties of the four storms derived from the MODIS collection 6 (Baum et al, 2012) and ERA5 at 0.25° × 0.25° resolution MUDIAR ET AL.…”

“…However, recent investigations on the raindrop size distribution (RDSD) in tropical SE cloud brings out another intriguing explanation of the presence of larger drops in this fraction of cloud. In a series of papers, Mudiar et al (2018), (Mudiar, Pawar, Hazra et al, 2021, Mudiar, Pawar, Gopalakrishnana et al, 2021 have shown that the prevailing stronger electric environment inside the SE cloud can facilitate the production of larger raindrops at the surface. They have shown that the cloud electric field can efficiently induce coalescence growth of the raindrops, thereby producing larger raindrops.…”

Relationship Between Convective Storm Properties and Lightning Over the Western Ghats

“…In a case study approach, Mudiar et al. (2018) utilized lightning network observations to delineate the presence of higher concentration of bigger raindrops in strongly electrified storms owing to enhancement in collision‐coalescence processes over the WG. Theoretical studies by Davis (1964) and Schlamp et al.…”

“…The advection of moisture laden south-west monsoon winds, heated land surface (Kamra & Ramesh Kumar, 2021) accompanied by strong updrafts across complex topography (Vishnu et al, 2013) are the major causes of lightning over the mesoscale mountain ranges of Western Ghats (WG). In a case study approach, Mudiar et al (2018) utilized lightning network observations to delineate the presence of higher concentration of bigger raindrops in strongly electrified storms owing to enhancement in collision-coalescence processes over the WG. Theoretical studies by Davis (1964) and Schlamp et al (1976Schlamp et al ( , 1979 have shown that strong electric fields and surface charges of raindrops inside the cloud can increase the coalescence efficiency upon collision between the drops.…”