Light microscope photography in a cold room laboratory of the Geography faculty of Lomonosov Moscow State University

. At the Faculty of Geography of Lomonosov


Introduction
In June 2023, the average air temperature in the Northern Hemisphere was +20.715℃, which is the highest indicator in the entire history of observations.This value is 0.572℃ higher than the climatic norm for the period 1991-2020, and as the temperature on the planet temporarily exceeded 1.5°C, according to data provided by the European Earth Observation Program Copernicus.So since the beginning of the industrial era, the average global temperature has risen by 1.1 degrees Celsius.This has led to a series of climatic events including increased storms, prolonged droughts, more frequent forest fires and warmer winters in the cold and temperate zone, and changes in the structure and properties of snow, ice and frozen ground.
Since snow cover, ice and frozen soils are important indicators of climate change and play an important role in the balance of surface energy [1], interaction of the surface with the atmosphere [2], and hydrological processes [3], at the Faculty of Geography of Lomonosov Moscow State University is equipped with a cold room to study their properties of snow, ice and frozen ground.The classification of snow cover is based mainly on the division into internal physical parameters and processes of snow cover formation (snow cover granularity, snow cover density, snow cover hardness, snow cover height, snow cover water content, snow cover duration, snow temperature, etc.) [4,5,6,7].The study of the properties of snow cover, ice and frozen soil in the cold room is used primarily for the needs of the educational process and scientific research at the Department of Cryolithology and Glaciology and the Laboratory of Snow Avalanches and Mudflows of the Faculty of Geography.In particular, the cold laboratory is equipped for lite microscope photography in polarized light, including using LoMo and Carl Zeiss microscopes and AxioVision image acquisition systems.

Microphotography of snowflakes
For microphotography of snowflakes in a cold room, the following actions were performed: to catch snowflakes at a certain ambient temperature, if they are falling at the moment, or to use previously caught snowflakes and photograph them and compare their shape with the Nakai diagram Ukichiro dependence of the shape of snowflakes on air temperature.
Diagram for the classification of snowflakes according to the conditions of their origin from Nakaya Ukichiro Snow Crystal Morphology Diagram [8,9] is shown in Figure 1.Snowflakes were caught in chilled bottles with machine oil and brought into a cold room with a microscope for photography.As a result, the shapes of crystals of precipitated solid precipitation were determined at a given ambient temperature, and the results were compared with theoretical data.The appearance of the installation for microphotography in a cold room is shown in Figure 2.An example of the classification of snowflakes obtained by the author is shown in Figures 3 and 4. Thus, by obtaining the corresponding images of snowflakes based on the results of microscopy, it is possible to establish a correspondence with the classification diagram of the temperature of their formation Nakaya Ukichiro Snow Crystal Morphology Diagram [8,9].

Microphotography of ice crystals
Also, in a cold room, ice samples were photographed in polarized light on a table with polarized light illumination and through a second polaroid located on a tripod.The appearance of the installation is shown in Fig. 5.According to the data of the book by Solomatin V.I. "Physics and geography of underground glaciation" [10], according to the sizes of crystals in elementary veins obtained petrographic observations (taking into account the width of the latter, the mineralogical and granulometric composition of the walls limiting the elementary vein), it is possible, using experimental curves, to determine the temperature of the walls of the cavity during the period filling it with water and crystallization of ice.Thus, by obtaining the corresponding structural parameters of elementary vein ice based on the results of microscopy, it is possible to determine the temperature of the rock during their formation.

Conclusion
The work was carried out in accordance with the state budget theme "Evolution of the cryosphere under climate change and anthropogenic impact" (121051100164-0), "Danger and risk of natural processes and phenomena" (121051300175-4).The authors declare no conflict of interest.

Fig. 1 .
Fig. 1.Diagram for the classification of snowflakes according to the conditions based on their origin from Nakaya Ukichiro Snow Crystal Morphology Diagram [8, 9].

Fig. 2 .
Fig. 2. External view of the installation for microphotography of snowflakes.

Fig. 5 .
Fig. 5. External of the installation for photographing in polarized light.An example of an image of ice in polarized light with clearly visible outlines of individual crystals is shown in Fig. 6.

Fig. 6 .
Fig. 6.An example photograph of ice in polarized light