The relationship between lightning activity and ice fluxes in thunderstorms

the relationship between lightning activity and ice fluxes in thunderstorms

the geographical thunderstorm characteristics – e.g., Tapia et al. (), Soula et al. Relationships between lightning activity and cloud microphysical structure . and nonprecipitating ice mass and estimated fluxes, as well. well as a tool for improving weather forecasting of convective storms and heavy rainfall. The relationship between lightning activity and ice fluxes in thunder-. downward flux of solid precipitation through the body of the thundercloud would not be surprising to find strong relationships between lightning activity and.

Relationship between Cloud Ice Size and Lightning In order study the relationship between cloud ice size and lightning in detail we have analyzed the monthly mean cloud effective radius and total lightning for the period — averaged over the continental L1, L2, and L3 and oceanic O1, O2, and O3 areas shown in Figure 1 d.

Months corresponding to the cloud ice size between 19 and 34 m are grouped in the bin size of 1 m we have considered all the months months for frequency count. We have noticed that there were hardly any months in which monthly mean cloud ice size was less that 19 m or greater than 34 m during the study period. Lightning corresponding to each bin of 1 m is then added to obtain total lightning for every 1 m bin between 19 and 34 m. Figure 2 shows relationship between cloud ice size and lighting over the three different continental Figure 2 a and oceanic regions Figure 2 b.

It can be seen that relationship between lighting and cloud ice size shows similar pattern over both continental and oceanic regions. Maximum lightning occurred for the mean ice cloud sizes of 24, 25, and 23 m over the continental regions L1, L2, and L3, respectively.

Similarly, over the oceanic regions O1, O2, and O3 maximum lightning occurred for the slightly greater mean cloud ice size of 26, 24, and 28 m, respectively.

Relationship between Size of Cloud Ice and Lightning in the Tropics

It is interesting to note from Figure 2 that total lighting increases with increase in the cloud ice size, attains maximum at certain cloud ice size, and after that starts decreasing with increasing cloud ice size. In order to understand this relationship we have analyzed vertical distribution of cloud ice concentration and relationship between cloud size with ice concentration over the continental and oceanic region.

Figures 3 a and 3 b show the cloud ice concentration at different altitude averaged during — period over the continental region L1 and oceanic region O2, respectively. It can be seen that ice concentration increases from altitude of 6 km, attends maximum concentration around 8—11 km over L1 and 10—14 km over O2 region, and decreases nearly to zero concentration at 18 km.

Figure 4 shows the distribution of cloud ice concentration as a function of mean cloud size at an altitude of 12 km near to same height over L1 and O2 regions, respectively. It can be seen from Figure 4 that ice concentration over L1 and O2 regions increases with respect to ice size up to 24 m, attends maximum concentration at 24 m, and ice concentration decreases with ice size above 24 m.

Similar relationship between ice concentration and ice size is also seen for the altitudes ranged between 8 and 14 km not shown here. The charge is generated due to growth of ice size by condensation deposition, combination of collection, etc.

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This process enhances the electric filed inside the cloud and generate lightning. During convection, cloud ice grows its size by combination of collection and condensation or deposition. The increasing ice concentration with respect to mean ice size from 19 to 24 m in Figure 4 can be attributed to the growth of ice size. Therefore, generated charge due to collision and condensation increases with increasing the ice concentration and attends the maximum charge with the maximum ice concentration at 24 m inside the cloud.

Hence, increasing lightning frequency with increasing the ice concentration with respect to ice size from 19 to 24 m with maximum lightning at 24 m can be seen in Figure 2.

the relationship between lightning activity and ice fluxes in thunderstorms

Takahashi [ 27 ] has also found increase in lightning with increase in the ice concentration and ice size, compliments to our results. The latent heat is generated during condensation or deposition increases the updraft velocity of the hydrometers, which enhances the hydrometers concentration at high altitude Figure 3 as well as electric filed inside the cloud.

Ziegler and MacGorman [ 44 ] and Dey et al. This is consistent with Figure 3 where we observed maximum ice concentration between 8 and 14 km altitude ranges.

It can also be seen from Figure 3 that although maximum ice concentration over both land and oceanic regions are found approximately in same altitude range 8—14 kmyet less lightning occurs over oceanic region. It might be due to weak updraft velocity in mix-phase region over ocean as compared to continental region.

Distribution of cloud ice concentration as a function of altitude averaged during — period a over the continental region L1 and b oceanic region O2. Relation between mean cloud ice size and cloud ice concentration averaged during — period at 12 km altitude a over the continental region L1 and b oceanic region O2. On the other hand, increased size of cloud ice increases its terminal velocity and thereby reduces the uplift velocity.

Therefore, larger particle descends isothermally towards the ground and begins to melt [ 45 ].

In this case charge with opposite polarity is also generated on hydrometer [ 43 ], however, unable to generate the charge to produce the lightning due to slow sublimation and low concentration of ice. Takahashi [ 4 ] also showed that the charge transfers per collision slow down with increase in ice diameter size.

Therefore, the negative relationship between total lightning and mean cloud ice size which is greater than 26—28 m instead of positive correlation for the size less than 19—25 m can be seen in Figure 2.

It is reasonable to conclude from Figures 23and 4 that the highest mean ice size of around 24 m contributes to maximum ice concentration in the altitude range between 8 and 14 km and therefore results in the maximum lightning over land and oceanic regions for ice size of around 23—26 m seen in Figure 2.

These imply that the relationship between mean ice size and lightning is curve linear. We have examined the association of lightning flashes with mean ice size over these regions. A clear spatial change in lighting and cloud ice size from spring to winter season is seen.

In general, total lightning is observed higher over the continental regions as compared to the lightning observed over oceanic region, whereas mean cloud ice size is observed higher over the oceanic region compared to the continental region during all the seasons.

It is observed that the relationship between lightning and mean cloud ice size is same over both continental and oceanic regions. It is also observed that maximum lightning occurred for the mean cloud ice size of around 23—25 m over the continental region and mean cloud ice size of around 24—28 m over the oceanic region.

However, for the first time, we found that relationship between lightning and mean cloud ice size follows the curve linear pattern and is not linear. We found that total lighting increases with increase in the cloud ice size and attends maximum at certain cloud ice size, then lightning decreases with increasing cloud ice size. The altitude profile show increase in ice concentration from 6 km, attends maximum concentration around 8—11 km over continent and 10—14 km over oceanic region, and decreases to zero concentration at around 18 km.

Ice concentration within this region shows maximum around 24 m. This concludes that maximum lightning observed around 23—25 m over the continental region and 24—28 m over the oceanic region is associated with the large ice concentration at around 24 m. Conflict of Interests The authors declare that there is no conflict of interests regarding the publication of this paper. D15, Article ID D, All radar data are corrected for attenuation and differential attenuation Bringi et al.

the relationship between lightning activity and ice fluxes in thunderstorms

Individual thunderstorms are identified and semi-objectively tracked using the Thunderstorm Identification Tracking Analysis and Nowcasting TITAN; Dixon and Wiener algorithm to assign radar and lightning characteristics to individual storms. This tracking method is the same used in previous lightning jump studies Schultz et al.

Vertical velocity retrievals are calculated using radial velocity measurements from two or more radars and a reflectivity based hydrometeor fall speed relationship to solve a set of linear equations e.

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Horizontal velocity components u and v derived from radial velocity measurements from both radars and are used to solve for the vertical velocity component w by integrating the anelastic continuity equation.

Similar to Schultz et al. The advantage of the variational integration technique is that it redistributes errors from both boundary conditions to produce profiles of vertical air motion and divergence that converge to a solution O'BrienMatejka and Bartels The downward integration scheme could also be utilized for similar analysis of updrafts.

Integration of the anelastic mass continuity equation is performed from the upper and lower bounds of integration for all points within the multi-Doppler domain. Upward integration is performed from 0 km up to 3 km and downward integration is performed from the upper boundary from 17 km down to and including 3 km.