Supercooled Cloud Tunnel Studies on the Growth of Snow Crystals between-4 and-20&amp;deg;C

Takahashi, Tomoki; Fukuta, N.

doi:10.2151/jmsj1965.66.6_841

Cited by 41 publications

(76 citation statements)

References 16 publications

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“…The 10-min duration is less than our earlier studies (Takahashi and Fukuta 1988;Takahashi et al 1991), but the longer growth times produce greater amounts of riming, more cases with spatial branches, and greater chances of drifting into the wall. Despite the shorter growth time, the stellar and dendrite crystals nevertheless have sizes typical of crystals in nature.…”

Section: Methodsmentioning

confidence: 53%

“…The vertical supercooled cloud tunnel used here is the same as that in Takahashi et al (1991). In the tunnel, a snow crystal can be suspended freely and grown in a vertical stream of artificially generated supercooled cloud by applying aerodynamic mechanisms for horizontal stability and by continuously adjusting the upward wind speed to match that of the (generally increasing) crystal fall speed.…”

Section: Methodsmentioning

confidence: 99%

“…To this end, a vertical supercooled cloud tunnel was developed in which a single snow crystal could be freely suspended and continuously grown in front of the observer (Takahashi and Fukuta 1988;Takahashi et al 1991;Fukuta and Takahashi 1999). The tunnel can simulate the process by which a snow crystal continuously grows while falling in a natural cloud.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Liquid Water Content and Temperature on the Form and Growth of Branched Planar Snow Crystals in a Cloud

Takahashi

2014

Journal of the Atmospheric Sciences

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How liquid water content (LWC) and temperature affect the growth of branched planar snow crystals is poorly understood. To address this issue, a vertical supercooled cloud tunnel was used to grow 167 individual snow crystals for 10 min under nearly constant conditions. The LWC varied within 0.07-0.76 g m 23 and average temperature varied from 212.48 to 216.38C, with the latter varying by at most 0.28C per run.The crystal habits are divided mainly by temperature, warm to cold, into nine regions: sector above 212.58C; then broad branch to 213.08C; and then stellar, dendrite, and fern to 214.58C. Then the pattern reverses, with dendrite to 214.88C, stellar to 215.78C, broad branch to 216.18C, and finally sector. From 213.38 to 213.88C, stellar changes to dendrite with LWC increase as well as with temperature decrease. From 213.88 to 214.58C, dendrites coexist with ferns below an LWC of 0.25 g m 23 , but only ferns exist at higher LWC. At other temperatures, a higher LWC does not produce greater side-branch development. Nevertheless, an increase of LWC produces heavier crystals (particularly crystals larger than 1 mm across), despite the crystal diameters being independent of LWC. Stellars at 214.98C have the maximum mass and diameter, whereas ferns at about 214.38C have the maximum basal-plane area and minimum fall speed. The apparent crystal density varies with temperature, with two local minima for stellars near 213.38 and 215.38C and a local maximum for ferns near 214.28C.

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Section: Methodsmentioning

confidence: 53%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Liquid Water Content and Temperature on the Form and Growth of Branched Planar Snow Crystals in a Cloud

Takahashi

2014

Journal of the Atmospheric Sciences

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“…However, a lack of observations in mixed-phase clouds (resulting from the challenge of detecting layers of supercooled liquid water in the ice-dominated parts of clouds) impeded an accurate computation of the liquid water content (LWC)-to-IWC ratio, which therefore limits an understanding of phase partitioning (Kalesse et al, 2016). Wind tunnel experiments by Takahashi and Fukuta (1988) and Fukuta and Takahashi (1999) measured the riming enhancement as an increase in ice particle fall speed (V ). They also showed that riming has a peak at −10.5 • C for low LWCs, where ice particles are isometric, and therefore have higher V .…”

Section: Characteristics Of Rimingmentioning

confidence: 99%

Growth of ice particle mass and projected area during riming

Erfani

Mitchell

2017

Atmos. Chem. Phys.

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Abstract. There is a long-standing challenge in cloud and climate models to simulate the process of ice particle riming realistically, partly due to the unrealistic parameterization of the growth of ice particle mass (m) and projected area (A) during riming. This study addresses this problem, utilizing ground-based measurements of m and ice particle maximum dimension (D) as well as theory to formulate simple expressions describing the dependence of m and A on riming. It was observed that β in the m − D power law m = α D β appears independent of riming during the phase 1 (before the formation of graupel), with α accounting for the ice particle mass increase due to riming. This semi-empirical approach accounts for the degree of riming and renders a gradual and smooth ice particle growth process from unrimed ice particles to graupel, and thus avoids discontinuities in m and A during accretional growth. Once the graupel with quasispherical shape forms, D increases with an increase in m and A (phase 2 of riming). The treatment for riming is explicit, and includes the parameterization of the ice crystal-cloud droplet collision efficiency (E c ) for hexagonal columns and plates using hydrodynamic theory. In particular, E c for cloud droplet diameters less than 10 µm are estimated, and under some conditions observed in mixed-phase clouds, these droplets can account for roughly half of the mass growth rate from riming. These physically meaningful yet simple methods can be used in models to improve the riming process.

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“…Circles and triangles indicate graupel embryos and graupel particles, respectively. Takahashi and Fukuta (1988), even isometric crystals such as columns and thick plates initiated at temperatures of @À10 C, which are considered the most promising candidate of graupel embryos, would grow in 10 minutes into densely rimed snow particles of 0.3 mm. The terminal fall velocity of the densely rimed snow particles would be @35 cm s À1 and the falling distance for ten minutes after the ice initiation would be, at most, 100 m and negligibly small.…”

Section: Discussionmentioning

confidence: 99%

The Precipitation Process in Convective Cells Embedded in Deep Snow Bands over the Sea of Japan

Murakami¹,

Yamada²,

Matsuo³

et al. 2003

Journal of the Meteorological Society of Japan

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Convective cells in two deep snow bands were examined over the Sea of Japan with an instrumented aircraft and dual-Doppler radars. A combination of the relatively warm air stream (westerly) at lower levels secluded near the center of the low and the polar air stream (west-southwesterly) at middle and upper levels produced a deep unstable stratification to the southwestern quadrant of a well-developed low, where snow bands A1 and B1 were respectively observed at around 1600 and 1700 JST on 28 Jan. 1993.Radar data showed that both snow bands were in quasi-steady state within a dual Doppler radar observation area. However, the two snow bands showed quite different development; the maximum reflectivities in bands A1 and B1 were 15 dBZ and 30 dBZ, respectively.Aircraft data showed that the accretional growth of snow particles was the primary precipitation formation mechanism in the convective cells embedded in both snow bands.From aircraft and radar data, it appears that vertical wind shear within the cloud layer influenced the precipitation process. In the cell embedded in snow band A1, the updraft at middle and upper levels tilted downshear due to a strong wind shear and precipitation embryos initiated in the updraft were advected downshear from the main supercooled cloud water region. Therefore, these embryos did not grow to large graupel particles. By comparison, in the cell embedded in snow band B1, the updraft tilted upshear at lower levels and stood almost erect at middle and upper levels due to weak wind shear. Therefore, precipitation embryos initiated in the updraft grew into 5 mm graupel particles as they descended through the main supercooled cloud water region. In addition, re-circulation of graupel particles, which had descended in a vicinity of the updraft core, seemed to play an important role to efficiently produce larger graupel particles.

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Supercooled Cloud Tunnel Studies on the Growth of Snow Crystals between-4 and-20°C

Cited by 41 publications

References 16 publications

Influence of Liquid Water Content and Temperature on the Form and Growth of Branched Planar Snow Crystals in a Cloud

Influence of Liquid Water Content and Temperature on the Form and Growth of Branched Planar Snow Crystals in a Cloud

Growth of ice particle mass and projected area during riming

The Precipitation Process in Convective Cells Embedded in Deep Snow Bands over the Sea of Japan

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