[MIS07-P02] 旭岳で光学顕微鏡を用いて観察した雪の結晶の昇華と再成長
キーワード：雪、その場観察、干渉計、光学顕微鏡法
To understand characteristic properties of water and its phase transition processes via nucleation and subsequent growth, we performed in-situ observation experiment using real snow crystals at the base of Asahi-dake in the Taisetsu area, Hokkaido, Japan. We stayed there 11 nights in total for four winter seasons from 2015 to 2018 and observed sublimation and regrowth processes of snow crystals using originally designed experimental systems; the Maki-type laser interferometer (modified Mach–Zehnder-type interferometer), the Michelson-type white-light interferometer microscope with a long working distance, the optimized color-filtered optical microscopes, a polarized optical microscope and so on. We also prepared an environment controllable cell using a Peltier cooling unit, which has a water vapor source with a heater and a chromel-alumel thermocouple, windows for optical observation, capillary to handle a snow crystal and a platinum resistance temperature detector for temperature measurement of the cell.
At first, we make one or two igloo-like snow laboratories (snow-lab) and set up optical systems in the snow-lab. Typical ambient temperature in the Taisetsu area is around -10 to -20oC and inside temperature of the snow-lab is slightly increased to be -5 to -11oC due to experimental systems such as illumination lights, monitor and camera in addition to heat of active observers. The humidity has been naturally controlled close to 100% because all the walls of the snow-lab have been made of snow, which also works as a good sound and vibration absorber.
We collected snow crystals directly on a black felt just outside the snow-lab and selected a snow crystal, which was put onto a glass plate for general observations of the shape and surface textures or onto the tip of the glass rod smaller than 1 mm in diameter to observe rates for sublimation and regrowth at a certain environment. Interference fringes made using a reflection light from a surface of a snow crystal were successfully observe by the Michelson-type white-light interferometer microscope. In this presentation, we will report our attempts of in-situ observation and the results including temperature and humidity dependent rates of sublimation and regrowth of a snow crystal observed using our experimental systems.
Acknowledgments: We thank Y. Sato, Y. Hirata, S. Nakatsubo and K. Fujita of the Technical Division in the Institute of Low Temperature Science, Hokkaido University, for their help in the development of the experimental system. This study was supported partly by the Grant for Joint Research Program of the Institute of Low Temperature Science, Hokkaido University and by a Grant-in-Aid for Scientific Research (S) from KAKENHI (15H05731).
At first, we make one or two igloo-like snow laboratories (snow-lab) and set up optical systems in the snow-lab. Typical ambient temperature in the Taisetsu area is around -10 to -20oC and inside temperature of the snow-lab is slightly increased to be -5 to -11oC due to experimental systems such as illumination lights, monitor and camera in addition to heat of active observers. The humidity has been naturally controlled close to 100% because all the walls of the snow-lab have been made of snow, which also works as a good sound and vibration absorber.
We collected snow crystals directly on a black felt just outside the snow-lab and selected a snow crystal, which was put onto a glass plate for general observations of the shape and surface textures or onto the tip of the glass rod smaller than 1 mm in diameter to observe rates for sublimation and regrowth at a certain environment. Interference fringes made using a reflection light from a surface of a snow crystal were successfully observe by the Michelson-type white-light interferometer microscope. In this presentation, we will report our attempts of in-situ observation and the results including temperature and humidity dependent rates of sublimation and regrowth of a snow crystal observed using our experimental systems.
Acknowledgments: We thank Y. Sato, Y. Hirata, S. Nakatsubo and K. Fujita of the Technical Division in the Institute of Low Temperature Science, Hokkaido University, for their help in the development of the experimental system. This study was supported partly by the Grant for Joint Research Program of the Institute of Low Temperature Science, Hokkaido University and by a Grant-in-Aid for Scientific Research (S) from KAKENHI (15H05731).