The Variability of the Water Contents of Tropical Cumuli

Ackerman, Bernice

doi:10.1175/1520-0469(1959)016<0191:tvotwc>2.0.co;2

Cited by 25 publications

(11 citation statements)

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“…Therefore, to augment previous studies of these topics (e.g. Malkus 1954;Malkus and Ronne 1954;Ackerman 1959;Leary and Houze 1979;Gamache 1990;Yuter and Houze 1998), it is an appropriate time to report on recent measurements of the microstructures of tropical clouds and the processes by which they produce precipitation. This paper is based on in situ measurements obtained aboard the University of Washington's (UW) Convair-580 research aircraft in the TRMM/Kwajalein Experiment (KWAJEX), which was carried out in the intertropical convergence zone in the vicinity of the Kwajalein Atoll, Republic of the Marshall Islands ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Microstructures and precipitation development in cumulus and small cumulonimbus clouds over the warm pool of the tropical Pacific Ocean

Rangno

Hobbs

2005

Quart J Royal Meteoro Soc

111

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SUMMARYIn situ airborne measurements obtained in convective clouds in the vicinity of the Marshall Islands on 15 days in July and August 1999 are used to determine the microphysical structures and precipitation-producing mechanisms in these clouds. The liquid water contents of the clouds were generally well below adiabatic values, even in newly risen turrets. This is attributed to the entrainment of ambient air and to the very efficient removal of cloud water by the collision and coalescence of drops. The formation of raindrops began when the concentration of droplets with radii >15 µm exceeded ∼3 cm −3 or, equivalently, when the effective cloud drop radius reached ∼13 µm. Clouds rained when their depth exceeded ∼1.5 km. Due to rainout, the effective radius of cloud droplets began decreasing ∼2-4 km above cloud base.Extremely high concentrations of ice particles (often >500 litre −1 ) formed very rapidly at temperatures between −4 and −10 • C. High-resolution imagery of these particles, which were primarily sheaths, needles, frozen drops and irregular ice fragments, indicates that the high concentrations of ice were initiated by the freezing of individual drops, some of which fragmented upon freezing, accompanied by ice splinter production during riming. However, for ice particles <100 µm in maximum dimension, frozen drops and ice fragments were much more numerous than columnar ice crystals, the latter being indicative of ice splinter production. Narrow (10-50 m wide) streamers of precipitation containing large (>3 mm diameter) solid and liquid particles were often encountered in growing clouds. It is proposed that the particles in these streamers grew rapidly by riming in water-rich zones and, under appropriate conditions, the ice particles produced by both drop fragmentation and riming resulted in exceptionally high localized concentrations of ice. Convective clouds consisting entirely of liquid water produced rain rates that were similar to those from deep convective clouds containing ice.Since the concentration of drizzle and raindrops within a few kilometres of cloud base was highly correlated with cloud depth, and therefore cloud top temperature, the concentration of raindrops in cumulus and cumulonimbus clouds over the warm pool of the tropical Pacific Ocean can be inferred from satellite measurements of cloud top temperatures.

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Section: Introductionmentioning

confidence: 99%

Microstructures and precipitation development in cumulus and small cumulonimbus clouds over the warm pool of the tropical Pacific Ocean

Rangno

Hobbs

2005

Quart J Royal Meteoro Soc

111

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“…WARNER, 1955) and has been used widely Tellus XVII (1965), 4 32* -652893 also by others (cf. ACKERMAN, 1959 and. The results obtained from clouds of various types indicate an average content varying 0.2 and 0.6 grn+ of air, on occasions up to 1.6, and in general much below the values expected from condensation due to wet-adiabatic aacent of moist air, indicating rather strong mixing with environmental air within the clouds.…”

Section: Summermentioning

confidence: 82%

Deuterium and oxygen-18 in precipitation and other natural waters Some theoretical considerations

Eriksson¹

1965

TellusA

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In the paper an attempt is made to express the isotope concentration in precipitation as a function of the atmospheric process which transport water vapor. It is found that the fractionation which takes place is considerably less when the atmospheric transport is due to eddy motion than when transport is simply advective. In the latter case fractionation follows the Rayleigh condensation formula. In the case of eddy transport fractionation may under special circumstances follow the same formula although with a factor (I/& -1) instead of ( a -1). More complicated transport patterns in the atmosphere are rather difficult to express mathematically.As to the vertically integrated transport it is at present difficult to derive explicit relations over ocean areas because of the exchange which takes place between air and water. Over continents, however, the relation can be formulated more explicit under certain conditions. Available data show a general relation bet,ween oxygen-18 and precipitable water which indicates that eddy transport is of major importance for distributing water vapor in the atmosphere.As to isotope concentrations in surface waters, exchange of water between air and liquid water is rather important and cannot be neglected in cases where data are applied t o specific hydrologic problems.

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“…A correlation between the mean ice and water content IWC (horizontal average) and L or H has been already pointed out in tropical cumulus clouds (Ackerman, 1959), and the dependencies found by the author can be written as…”

Section: Correlationsmentioning

confidence: 99%

Statistical distributions of water content and sizes for clouds above Europe

Berton¹

2000

Ann Geophysicae

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Abstract. The statistics of quantities involved in the synthesis of cloud scenes have been investigated from an original data base. Frequency distributions of ice and water content (IWC), horizontal and vertical sizes (L and H), and top temperatures (T) of clouds above Europe have been derived for nine types of clouds (As, Cb, Ci, Cg, LwCg, OrCg, Cs, Ns, Sc). It appears that the cumulated frequency plots can be well ®tted with log-normal or Weibull pro®les, and that for IWC and T cloud types can be split into two or three classes according to slopes in logarithmic coordinates. Crosscorrelation coecients between IWC, L, H and T have been also derived. Implications for the physics of the cloud build-up processes are brie¯y outlined. Critical analysis and comparison of other published results are proposed.

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The Variability of the Water Contents of Tropical Cumuli

Cited by 25 publications

References 0 publications

Microstructures and precipitation development in cumulus and small cumulonimbus clouds over the warm pool of the tropical Pacific Ocean

Microstructures and precipitation development in cumulus and small cumulonimbus clouds over the warm pool of the tropical Pacific Ocean

Deuterium and oxygen-18 in precipitation and other natural waters Some theoretical considerations

Statistical distributions of water content and sizes for clouds above Europe

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