## 6 Summary and Conclusions  
This paper presents data and images of falling snow and other hydrometeors in the size range from 50 \(\upmu\)m to 4 mm by the D-ICI during snowfall events in Kiruna, Sweden from 2014 to 2019. The D-ICI takes dual high-resolution images (side and top view) that enable a better shape classification than if there was only one image per particle. From these images, we were able to determine the particle size, cross-sectional area, area ratio, and aspect ratio of individual particles. We separated the particles into many different shapes following largely the Magono-Lee classification scheme. This resulted in an updated classification with 135 shapes, including 34 new shapes found in Kiruna during this period, which are shown in Figures 11 and 12. The new shapes are highlighted by gray frames. Table 11 (Appendix A) lists the full names of all the shapes, and the new shapes are denoted _[KRN]_. This study sought to find some characteristic microphysical properties, particle size, cross-sectional area, area ratio, aspect ratio, and frequency of occurrence of similar shapes. To facilitate this, we further sorted the 135 shapes into 15 shape groups based on morphological similarity. Naturally, it is also possible and, for some applications, more suitable to choose fewer groups. Tables 4-7 (Section 4) show detailed descriptions of each of these groups, and a list with the complete names of the particle shapes sorted into the shape groups is given in Table 12 (Appendix B). The main conclusions of this study can be summarized as follows:  
* The dual images provides more information about the particle shape. * We found 34 snow particles that are not yet described and that warrant their own shape in the updated shape classification. * In our dataset, shape groups _(1) Needles and thin or long columns_, _(8) Branches_, _(9) Side planes_, and _(14) Irregulars and aggregates_ are the most common, occurring more often than 10% of the time. * Shape group _(6) Stellar crystals_ has the largest median particle size, \(D_{\text{max}}=1450\)\(\upmu\)m, followed by shape groups _(2) Crossed needles and crossed columns_, _(7) Bullet rosettes_, _(8) Branches_, _(9) Side planes_, and _(11) Spatial stellar crystals_ with \(D_{\text{max}}>1000\)\(\upmu\)m. Shape groups _(3) Thick columns and bullets_,  
Figure 6: Area ratio versus aspect ratio (\(A_{\text{r}}\) vs. \(A_{\text{s}}\)) relationships for each shape group (solid lines) and for all data regardless of shape (black dashed lines) are shown. Fits for the \(A_{\text{r}}\) vs. \(A_{\text{s}}\) relationship are given by Equation (5). The median \(A_{\text{s}}\) is represented as a single point on each line. The lengths of the fit lines are defined by the percentiles 15.9% and 84.1% of \(A_{\text{s}}\). For comparison, spherical particles are shown (\(A_{\text{r}}=A_{\text{s}}\)) as dashed gray line. For a legend, see Figure 4. Data are shown in Table 9.  
(5) Plates, (13) Ice and melting or sublimating particles, and (15) Spherical particles have the smallest \(D_{\rm max}<500\) um (see Figure 4a). * Shape group (6) Stellar crystals also has the largest median cross-sectional area, \(A=6.34\times 10^{-7}\) m\({}^{2}\), followed by shape groups (7) Bullet rosettes, (8) Branches, (9) Side planes, and (11) Spatial stellar crystals with \(A>3.0\times 10^{-7}\) m\({}^{2}\) (see Figure 4b). * In general, groups with large particle sizes also have large areas. However, there are exceptional shape groups with the largest particle sizes but with smaller areas, as it is in the case of shape group (2) Crossed needles and crossed columns. We can see in Figure 4c, in which we note that shape groups (1) Needles and thin or long columns, (2) Crossed needles and crossed columns, and (3) Thick columns and bullets have the smallest area ratios, \(A_{\rm r}<0.4\).