Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China
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<sub>2</sub>O<sub>2</sub>, sulfur(IV), organic carbon, and ele...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/17/9885/2017/acp-17-9885-2017.pdf |
| Summary: | 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<sub>2</sub>O<sub>2</sub>, 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 2007–2008 (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 (<i>N</i><sub>d</sub>) 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<sub>2. 5</sub> 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<sub>2. 5</sub> 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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| ISSN: | 1680-7316 1680-7324 |