Small ice crystals and the climatology of lightning (original) (raw)
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Relationship between Size of Cloud Ice and Lightning in the Tropics
Advances in Meteorology, 2014
The association of lightning flashes with mean cloud ice size over continental and oceanic region in the tropical areas has been analyzed using the observations from various satellite platforms (MODIS, TRMM, and LIS) for the period 2000–2011. We found that frequency of lightning in general is higher over the continental region compared to oceanic region, whereas larger size of cloud ice is observed over the oceanic regions compared to the continental regions. Relationship between lighting and cloud ice size shows similar features over both continental and oceanic regions. For the first time, we show that total lighting increases with increase in the cloud ice size; attends maximum at certain cloud ice size and then decreases with increase in cloud ice size. Maximum lightning occurred for the mean cloud ice size of around 23–25 µm over the continental region and mean cloud ice size of around 24–28 µm over the oceanic region. Based on our observation we argue that the relation between...
Journal of the Atmospheric Sciences, 2020
In this two-part paper, influences from environmental factors on lightning in a convective storm are assessed with a model. In Part I, an electrical component is described and applied in the Aerosol-Cloud model (AC). AC treats many types of secondary (e.g., breakup in ice-ice collisions, raindrop-freezing fragmentation, rime splintering) and primary (heterogeneous, homogeneous freezing) ice initiation. AC represents lightning flashes with a statistical treatment of branching from a fractal law constrained by video imagery. The storm simulated is from the Severe Thunderstorm Electrification and Precipitation Study (STEPS; 19/20 June 2000). The simulation was validated microphysically [e.g., ice/droplet concentrations and mean sizes, liquid water content (LWC), reflectivity, surface precipitation] and dynamically (e.g., ascent) in our 2017 paper. Predicted ice concentrations (;10 L 21) agreed-to within a factor of about 2-with aircraft data at flight levels (2108 to 2158C). Here, electrical statistics of the same simulation are compared with observations. Flash rates (to within a factor of 2), triggering altitudes and polarity of flashes, and electric fields, all agree with the coincident STEPS observations. The ''normal'' tripole of charge structure observed during an electrical balloon sounding is reproduced by AC. It is related to reversal of polarity of noninductive charging in ice-ice collisions seen in laboratory experiments when temperature or LWC are varied. Positively charged graupel and negatively charged snow at most midlevels, charged away from the fastest updrafts, is predicted to cause the normal tripole. Total charge separated in the simulated storm is dominated by collisions involving secondary ice from fragmentation in graupel-snow collisions.
Precipitation Ice and Lightning: From Global to Cell Scales
Theory predicts a close relationship between precipitation ice mass and lightning flash rates. To what degree and over what scales (global, regional, cell scale) are theoretical relationships between ice and lightning, with attendant assumptions, verified in observational data? Herein we review recent global observations of lightning and ice water path using results from the Tropical Rainfall Measurement Mission (TRMM) satellite Lightning Imaging Sensor (LIS), and extend these results to both regional and individual thunderstorm scales.
The relationship between lightning activity and ice fluxes in thunderstorms
Journal of Geophysical Research, 2008
1] It is generally believed that a strong updraft in the mixed-phase region of thunderstorms is required to produce lightning. This is the region where the noninductive charging process is thought to generate most of the storm electrification. Analytic calculations and model results predict that the total lightning frequency is roughly proportional to the product of the downward mass flux of solid precipitation (graupel) and the upward mass flux of ice crystals. Thus far this flux hypothesis has only been tested in a very limited way. Herein we use dual-polarimetric and dual-Doppler radar observations in conjunction with total lightning data collected in Northern Alabama and also Colorado/ Kansas during two field campaigns. These data are utilized to investigate total lightning activity as a function of precipitation and nonprecipitation ice masses and estimates of their fluxes for different storm types in different climate regions. A total of 11 storms, including single cell, multicell, and supercell storms, was analyzed in the two climatologically different regions. Time series of both precipitation and nonprecipitation ice mass estimates above the melting level show a good relationship with total lightning activity for the 11 storms analyzed (correlation coefficients exceed 0.9 and 0.8, respectively). Furthermore, the relationships are relatively invariant between the two climate regions. The correlations between total lightning and the associated product of ice mass fluxes are even higher. These observations provide strong support for the flux hypothesis.
The effects of aerosol particles on precipitation have been studied for several decades and it was shown that aerosols can either increase or decrease precipitation, depending on local thermodynamical, dynamical and microphysical conditions. The effect of aerosol particles on the electrification of storms and lightning production is less known; however, since precipitation and lightning in deep convective clouds are generated by the same physical processes, it can be expected that aerosol particles would also influence lightning. Recent local analyses of several regions of the earth indicate that the aerosol optical depth (AOD) is positively correlated with lightning density. Here, we explore this relationship globally for the four seasons of the year 2012. We use AOD data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite. Cloud to ground lightning events (those with the strongest peak currents) were recorded by the World Wide Lightning Loc...