The Relation Between Humidity and Liquid Water Content in Fog: An Experimental Approach

Gonser, S. G.; Klemm, Otto; Grießbaum, F.; Chang, Shih‐Chieh; Chu, Housen; Hsia, Yue-Joe

doi:10.1007/s00024-011-0270-x

Cited by 33 publications

(26 citation statements)

References 18 publications

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“…The mean values of N d ranged widely from 79 to 722 cm −3 and the mean values of LWC ranged widely from 0.01 to 0.39 g m −3 . Orographic cloud is a highly heterogeneous system consisting of randomly distributed air volumes with different characteristics (Gonser et al, 2012). This feature of orographic cloud generally determines the large differences in CDSD, LWC and aerosol composition of different cloud events.…”

Section: Microphysical Parametersmentioning

confidence: 99%

“…This was caused by the variation of LWC values or ambient RH in different monitoring moments (Ackerman et al, 2004). The low RH (representing insufficient water vapor in the atmosphere) would impede the hygroscopic growth of particles and the activation of droplets (Gonser et al, 2012;Liu et al, 2011), affecting the formation of cloud droplets.…”

Section: Interaction Between Aerosols and Cloud Chemical Propertiesmentioning

confidence: 99%

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Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China

Li¹,

Wang²,

Chen³

et al. 2017

Atmos. Chem. Phys.

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Abstract. The chemical composition of 39 cloud samples and droplet size distributions in 24 cloud events were investigated at the summit of Mt. Tai from July to October 2014. Inorganic ions, organic acids, metals, HCHO, H 2 O 2 , sulfur(IV), organic carbon, and elemental carbon as well as pH and electrical conductivity were analyzed. The acidity of the cloud water significantly decreased from a reported value of pH 3.86 during (Guo et al., 2012 to pH 5.87 in the present study. The concentrations of nitrate and ammonium were both increased since 2007-2008, but the overcompensation of ammonium led to an increase in the mean pH value. The microphysical properties showed that cloud droplets were smaller than 26.0 µm and most were in the range of 6.0-9.0 µm at Mt. Tai. The maximum droplet number concentration (N d ) was associated with a droplet size of 7.0 µm. High liquid water content (LWC) values could facilitate the formation of larger cloud droplets and broadened the droplet size distribution. Cloud droplets exhibited a strong interaction with atmospheric aerosols. Higher PM 2.5 levels resulted in higher concentrations of water-soluble ions and smaller sizes with increased numbers of cloud droplets. The lower pH values were likely to occur at higher PM 2.5 concentrations. Clouds were an important sink for soluble materials in the atmosphere. The dilution effect of cloud water should be considered when estimating concentrations of soluble components in the cloud phase.

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Section: Microphysical Parametersmentioning

confidence: 99%

Section: Interaction Between Aerosols and Cloud Chemical Propertiesmentioning

confidence: 99%

Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China

Li¹,

Wang²,

Chen³

et al. 2017

Atmos. Chem. Phys.

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show abstract

“…The physics and chemistry of fog has been studied by Chang et al (2006), Beiderwieden et al (2007), Gonser et al (2011), andEl-Madany et al (2013) at a meteorological tower extending about 10 m above the canopy height. The tower is surrounded by a 300 ha homogenous yellow cypress plantation with an average height of 14.8 m (Beiderwieden et al, 2007), a largely homogenous canopy, and a slope of 14% .…”

Section: Site Descriptionmentioning

confidence: 99%

Chemical Composition of Fog Water at Four Sites in Taiwan

Šimon

Klemm

El-Madany

et al. 2016

Aerosol Air Qual. Res.

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This study characterizes and compares the chemical composition of fog water at four sites in Taiwan. Fog was sampled with identical active fog collectors (modified Caltech design) using identical sampling strategies at all four sites. While the sites varied largely in terms of altitude above mean sea level (asl), type of fog, and the potential sources of constituents in fog water, the chemical composition of fog water was in all cases clearly dominated by H + , NH 4 + , NO 3 -and SO 4 2-, making up more than 85% of the total ion concentrations. The pH ranged from 2.27 to 5.95.Sulfur dioxide emissions from coal combustion in Mainland China and Taiwan as well as nitrogen oxide emissions from urbanized central-west Taiwan and the greater Taipei region were the main precursors of fog acidity. Ammonia, originating from agriculture emissions, was the main neutralizer. The Kinmen site (48 m asl), situated on an island close to Mainland China, exhibited the lowest pH and the highest sulfate concentrations. At the Xitou site on the western slopes of the Taiwan Central Mountain Range (1150 m asl), ammonium from agriculture dominated and lead to relatively high pH. At the same time, the nitrate/sulfate ratio was highest at this site (> 1 in equivalent units), resulting from relatively large contributions from street traffic. The ion concentrations at the Chilan site (1650 m asl) and the Lulin high mountain site (2862 m asl) were much lower than those at Xitou and Kinmen. While the ion concentrations at Chilan were considerably lower than at Lulin, the ion loadings, which is the amount of dissolved ions per volume of air, were similar at Chilan and Lulin.

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“…The concentration of non-sea-salt sulfate (nss-SO4 2− ) was computed from the measured sulfate concentration minus the presumed contribution of sea salt, assuming that all sodium originates from sea salt and the average sodium/sulfate ratio in sea water: nss-SO4 ) [14]. The collection efficiency of the passive collector was estimated on the basis of Stoke's Law of impaction, the design of the collector, the measured wind speed, and an average droplet size spectrum from a Taiwan mountain site [15]. The overall collection efficiency with respect to the Liquid Water Content (LWC, mass of liquid water dispersed per volume of air, in units g·m ) was 90% for wind speeds above 2 m·s .…”

Section: −1mentioning

confidence: 99%

pH Control in Fog and Rain in East Asia: Temporal Advection of Clean Air Masses to Mt. Bamboo, Taiwan

et al. 2015

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Fog and rain was collected during an 18-day period in January 2011 at Mt. Bamboo, northern Taiwan. Almost 300 hourly fog samples and 16 daily rain samples were taken. One single fog sample (pH 3.17) was influenced by local volcanic activity, otherwise the pH ranged from 3.23 to 6.41 in fog and from 3.59 to 6.31 in rain. All the respective air masses arrived from the northeast, but exhibited two distinct groups: Group_1 had high concentrations of all ions (median interquartile range of total ion concentrations 3200-6200 µeq.·L ) and low pHs (median 3.52), the respective air masses had travelled over densely populated and industrialized regions of mainland China. Group_2 was from air masses with long travel times over the ocean and relatively low total ion concentrations (80-570 µeq.·L ) and higher pHs (median 4.80). The cleanest samples are among the cleanest reported in the literature of worldwide fog and rain. In both groups, the pH was governed by the balance of sulfate, nitrate, ammonium, and, in some cases, calcium. The variability of these ions was higher than the variability of 10 −pH , which shows that the pH is a rather robust parameter in contrast to its drivers such as non-sea-salt sulfate. OPEN ACCESSAtmosphere 2015, 6 1786

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The Relation Between Humidity and Liquid Water Content in Fog: An Experimental Approach

Cited by 33 publications

References 18 publications

Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China

Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China

Chemical Composition of Fog Water at Four Sites in Taiwan

pH Control in Fog and Rain in East Asia: Temporal Advection of Clean Air Masses to Mt. Bamboo, Taiwan

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