## 1 Introduction  
The shape of ice particles is an important characteristic that affects the radiative impact of clouds. Accurate knowledge of the microphysical properties of clouds, including particle shape, is important in order to assure accurate cloud parameterizations in climate and meteorological forecast models, e.g., that presented in References [1; 2]. Realistic cloud microphysical parameterizations are also essential for most cloud retrievals from satellite measurements. For instance, in order to retrieve quantities such as cloud water path or cloud effective radius, the underlying assumptions of particle shape, size, and distribution have a massive impact on the retrieval itself [3; 4]. The unavoidable sensitivity of satellite retrievals to assumptions on ice particle properties, such as particle size, area, and the shape of snow crystals, is one of the dominating sources of uncertainties in cloud retrievals [5]. Although satellite observations of clouds are important validation sources for models, the role of clouds still poses one of the most substantial uncertainties in modeling the climate [6]. The shape of the snow crystals, which this paper primarily concerns, is formed by deposition, riming, aggregation, or a combination of these mechanisms [7]. Deposition refers to the process of water vapor freezing (depositing) onto ice nuclei or an existing ice crystal. If the ice crystals are in an environment with supercooled water droplets, these droplets may collide with and freeze onto the crystals, forming an icy surface layer and riming the crystal. As the snow crystals grow, they are more likely to collide with one another and to join together in a process called aggregation. The snowflake typically encounters several different temperature and humidity environments as they grow, resulting in a great variety of shapes, such as needles, stellar, plates, and graupel [8; 9; 10; 11; 12; 13; 14; 15; 16; 17]. [PERSON] and [PERSON] [8] developed a snow crystal morphology diagram (\"Nakaya Diagram\") tying the growth conditions of snow crystals to water vapor supersaturation (relative to ice) and temperature. This diagram has been adapted and translated into English by [PERSON] [16]. In 1951, the International Commission of Snow and Ice (ICSI) and the International Association of Cryospheric Sciences (IACS) characterized snow crystals into ten main shapes: plates, stellar crystals, columns, needles, spatial dendrites, capped columns, irregular particles, graupel, ice pellets, and hail. This classification, called the \"Abstract of the International Classification for Snow\" [18], is still used to distinguish different types of snow, including snow on the ground [19]. However, for some purposes, a more detailed classification is desirable. [PERSON] [20] published a categorization scheme, still widely used, that catalogs snow and crystals into 80 categories. This classification scheme will, from now on, be referred to as the Magono-Lee classification. It divides shapes into categories and subcategories, allowing a logical shape labeling. For example, the shape \"CIf\" is a hollow, simple, columnar crystal, where C is columnar crystal, 1 is simple, and f is hollow. More recently, [PERSON] et al. [21] presented an extensive revision of the Magono-Lee classification which catalogs snow crystals and other solid precipitation particles into 121 categories. This revised classification uses levels and sublevels in a similar way to Magono-Lee. However, [PERSON] et al. [21] merged the two main levels \(N\) (needles) and \(C\) (columns), and consequently, some shapes that already existed in Magono-Lee received new labels. There are also situations where a less detailed classification with only a few shapes is more desirable to use. For instance, the Abstract of the International Classification for Snow by ICSI and IACS provides a less detailed classification.