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Volume 74, Issue 1
Displaying 1-3 of 3 articles from this issue
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chamber with the “FINEDEW” chilled mirror hygrometerAkio MURAI, Takao KAMEDA, Shuhei TAKAHASHI, Yukiya MINAMI2012 Volume 74 Issue 1 Pages 3-21
Published: 2012
Released on J-STAGE: September 03, 2022
JOURNAL OPEN ACCESSIn order to investigate the morphology of snow crystals from －4 ℃ to －40 ℃, artificial snow crystal formation experiments using a convection chamber with the “FINDEW” chilled mirror hygrometer were conducted about 200 times. Using the data of relative humidity in the atmospheric phase (RHi) by FINDEW, we made a new diagram of snow crystal types. Our main findings are as follows: 1)Snow crystals mostly generate from ice saturation level to water saturation level from －4 ℃ to －40 ℃. 2)When the humidity is close to the ice saturation level in the same temperature range, only columnar and thick plate types of snow crystals formed. When the humidity increases, snow crystals develop to each particular shape according to the temperature. Below －35 ℃ and over 105 ％ RHi a variety of shapes of snow crystals including poly-crystals formed. 3) Snow crystals sometimes formed below ice saturation level, which is difficult to understand. We postulate that small supercooled droplets, which are floating in the convection chamber, possibly attribute to the growth of snow crystals. 4)The relation between the growth rates and RHi was obtained for the needle type, the dendritic type and the crossed-plate type at temperatures above－30 ℃. On the other hand, no clear relations between the growth rates and RHi were observed for the sector plate type, the hexagonal plate type, and the crossed plates type at temperatures under －30 ℃.View full abstractDownload PDF (15743K) -
Dependence of tensile fracture strength of high-density wet snow on density and liquid-water contentYasushi KURIHARA, Katsuhisa KAWASHIMA, Kaoru IZUMI2012 Volume 74 Issue 1 Pages 23-31
Published: 2012
Released on J-STAGE: September 03, 2022
JOURNAL OPEN ACCESSTo clarify the tensile fracture strength of high-density wet snow, which can be seen in perennial snow patches of Japan during the ablation period, tensile fracture tests were carried out in a cold room at 0-1℃.Test specimens were taken from the Nishi-honjyozawa snow patch on Mt. Arasawa; these specimens had a dry density ranging from 497 to 855kg m-3 and liquid-water content ranging from 0％ to 16.1 ％ by weight. The test data showed the tendency of the tensile fracture strength to increase with dry density, although the data was scattered. This scatter indicates that the at the tensile fracture strength of high-density wet snow is highly dependent on density as well as liquidwater content. Therefore, after the relationship between the tensile fracture strength of dry snow and its density was formalized using the data obtained by Mellor (1975) in addition to this test data, the following relationship was obtained by taking into consideration the decreasing rate of tensile fracture strength in response to the increase in liquid-water content: σt ＝1.0 ×10-9ρdry4.17exp(0.058ω),where σt is the tensile fracture strength of high-density wet snow (kPa);ρdry,the dry density of wet snow (kg m -3); and ω, the liquid-water content （％ by weight). This empirical formula was found to be suitable for estimating the tensile fracture strength of high-density wet snow with sufficient accuracy.View full abstractDownload PDF (8203K) -
Norikazu MAENO, Shuhei TAKAHASHI, Atsushi SATO, Yasuhiro KOMINAMI, Hir ...2012 Volume 74 Issue 1 Pages 33-45
Published: 2012
Released on J-STAGE: September 03, 2022
JOURNAL OPEN ACCESSIndependent verification experiments of Mpemba effect were conducted by members of JSSI at five different universities and research institutes. Their results showed that the Mpemba effect could be observed but it was almost impossible to observe repeatedly even if the same initial temperatures of hot and cool waters and the surrounding environment were set. The difficulty of reproducibility was attributed to the fact that the delicate physical mechanisms directly related to the cooling of water such as heat conduction, evaporation, diffusion, convection, etc. are different in each experimental run because we cannot control them artificially. In case water supercools it appears as if Mpemba effect occurred, but supercooling is accidental and follows no regular physical rules.View full abstractDownload PDF (20356K)
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