In order to imitate the transport of snow in a pipe and to compare the calculated results of the pressure loss with the experimental results, some experiments were made by using the two kinds of polystyrene particles because the specific gravity of these particles was as same as the one of ice particles.
The test sections consisted of transparent acrylic pipes with 49.7mm i.d. and the pressure loss was measured by a manometer.
The coefficients of the pressure loss were calculated from Eq.(2). They showed the nega-tive values at high velocities even though the value of the specific gravity was larger than unity, and this result is the same as the one obtained by Shirakashi et al.
The results of the pressure loss were analyzed by three models, that is, Bingham flow model, Shook model and Moving bed flow model. The calculated values of the coefficients of the pressure loss by using these models were in good agreement with the experimental results.
However, these models have merits and demerits respectively, and they are listed in Table 2.

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A new detecting system for size of falling snow flakes is studied by optical sensing method. This system continuously covers 1 mm through 5 mm in radius. Falling velocity of snow flakes affects the system sensitivity, we tune it to about 60 cm/s in velocity. Test observation, performed for 1988's winter, shows that the new system works well and may be useful to detect the intensity of snow fall.

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"Ice monster" are the product of a peculiar icing phenomenon that is seen only in certain mountain areas in Tohoku Distrct, including Mt. Zao, Mt. Hatimanntai.
The ice-snow accretion (Ice monster) in Mt. Zao results from both icing and snow accretion and is a complicated compound phenomenon which requires wide-ranged experiments and observations to be explained and overcome. In this study, attention was directed to the environmental conditions that facilitate the development of ice monster, based on the topography of Mt. Zao, meteorological conditions, depth of the snow cover, and observations of the growth process of this peculiar phenomenon.
Several types of models for the Abies mariesii were prepered in order to determine the collection efficiency of snow particles and supercooled water droplets by these models. The observations were carried out on the development of ice-snow accretion. They shed light on unknown factors in the growth of the ice monster. Experiments were conducted at a low-temperature laboratory and a field station in Mt. Zao. The process of growth, rates of growth, adhering state of snow, etc., were measured ; and the data obtained were compared and discussed.

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