scholarly journals Influence of the ambient humidity on the concentration of natural deposition-mode ice-nucleating particles

2016 ◽  
Vol 16 (2) ◽  
pp. 927-932 ◽  
Author(s):  
M. L. López ◽  
E. E. Ávila
Keyword(s):  
Relative Humidity ◽  
Linear Trend ◽  
Ground Level ◽  
Ambient Air ◽  
Air Masses ◽  
Ambient Relative Humidity ◽  
Thermodynamic Conditions ◽  
Rainy Days ◽  
Deposition Mode

Abstract. This study reports measurements of deposition-mode ice-nucleating particle (INP) concentrations at ground level during the period July–December 2014 in Córdoba, Argentina. Ambient air was sampled into a cloud chamber where the INP concentration was measured at a temperature of −25 °C and a 15 % supersaturation over ice. Measurements were performed on days with different thermodynamic conditions, including rainy days. The effect of the relative humidity at ground level (RHamb) on the INP concentration was analyzed. The number of INPs activated varied from 1 L−1 at RHamb of 25 % to 30 L−1 at RHamb of 90 %. In general, a linear trend between the INP concentration and the RHamb was found, suggesting that this variability must be related to the effectiveness of the aerosols acting as INPs. From the backward trajectories analysis, it was found that the link between INP concentration and RHamb is independent of the origin of the air masses. The role of biological INPs and nucleation occurring in pores and cavities was discussed as a possible mechanism to explain the increase of the INP concentration during high ambient relative humidity events. This work provides valuable measurements of deposition-mode INP concentrations from the Southern Hemisphere where INP data are sparse so far.

scholarly journals Influence of the ambient humidity on the concentration of natural deposition ice nuclei

2015 ◽  
Vol 15 (12) ◽  
pp. 16697-16714
Author(s):  
M. L. López ◽  
E. E. Ávila
Keyword(s):  
Relative Humidity ◽  
Linear Trend ◽  
Ground Level ◽  
Air Masses ◽  
Ambient Humidity ◽  
Ambient Relative Humidity ◽  
Ice Nuclei ◽  
Thermodynamic Conditions ◽  
Rainy Days

Abstract. This study reports measurements of deposition ice nuclei (IN) concentration at ground level during the period July–December 2014 in Córdoba, Argentina. The measurements were carried out at temperature of −25 °C and at 15 % supersaturation over ice. They were performed on days with different thermodynamic conditions, including rainy days. The effect of the relative humidity at ground level (RHamb) on the IN concentration was analyzed. The number of IN activated varied from 1 −1 at RHamb of 25 % to 30 L−1 at RHamb of 90 %. In general, a linear trend between the IN concentration and the RHamb was found, suggesting that this variable must be related to the ability of the aerosols acting as IN. These results are consistent with previous results. From the backward trajectories analysis, it was found that the link between IN concentration and RHamb is independent of the origin of the air masses. The role of nucleation occurring in pores and cavities was discussed as possible mechanism to explain the increase on the IN concentration during high ambient relative humidity events.

Caking of sodium chloride: Role of ambient relative humidity in dissolution and recrystallization process

2013 ◽  
Vol 86 ◽  
pp. 78-86 ◽  
Author(s):  
Marina Langlet ◽  
Mohamed Benali ◽  
Isabelle Pezron ◽  
Khashayar Saleh ◽  
Pierre Guigon ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Relative Humidity ◽  
Recrystallization Process ◽  
Ambient Relative Humidity

Fluid Properties at Gas Turbine Inlet due to Fogging Considering Evaporation and Condensation Phenomena as Well as Icing Risk

2014 ◽  
Author(s):  
Christoph Günther ◽  
Franz Joos
Keyword(s):  
Relative Humidity ◽  
Gas Turbine ◽  
Ambient Air ◽  
Equilibrium Conditions ◽  
Evaporation And Condensation ◽  
The Third ◽  
Ambient Relative Humidity ◽  
Fluid Properties ◽  
Gas Turbine Compressor ◽  
Non Equilibrium

This study reports on numerically calculated thermophysical properties of air entering a gas turbine compressor after passing through an intake duct affected by different cooling techniques. Case of reference is unaffected ambient air (referenced to as unaffected) passing the intake duct. Furthermore ambient air cooled down to wet bulb temperature by (overspray) fogging (referenced to as wet) was considered. The third case shows air cooled down to the same temperature as it was reached in the wet case but by using chillers (referenced to as chilled). Equilibrium and non-equilibrium properties according to the occurring evaporation and condensation phenomena were compared. Equilibrium conditions seems to have a reduced inlet icing risk for the wet case compared to the chilled case. However comparing the wet case to the unaffected case showed a higher icing risk for the wet case at low ambient relative humidity. In contrast to equilibrium conditions a consideration of non-equilibrium conditions resulted in an increased icing risk due to almost negligible condensation rates.

Measurements of moisture in smoldering smoke and implications for fog

2006 ◽  
Vol 15 (4) ◽  
pp. 517 ◽  
Author(s):  
Gary L. Achtemeier
Keyword(s):  
Relative Humidity ◽  
Ground Level ◽  
Southern United States ◽  
Formation Temperature ◽  
Mixing Ratio ◽  
Prescribed Burns ◽  
Dry Air ◽  
Ambient Relative Humidity ◽  
Humidity Measurements ◽  
The Impact

Smoke from wildland burning in association with fog has been implicated as a visibility hazard over roadways in the southern United States. A project began in 2002 to determine whether moisture released during the smoldering phases of southern prescribed burns could contribute to fog formation. Temperature and relative humidity measurements were taken from 27 smoldering ‘smokes’ during 2002 and 2003. These data were converted to a measure of the mass of water vapor present to the mass of dry air containing the vapor (smoke mixing ratio). Some smokes were dry with almost no moisture beyond ambient. Other smokes were moist with moisture excesses as large as 39 g kg–1. Calculations show that ground-level smoke moisture excesses have no impact on ambient relative humidity during the day. However, the impact at night can be large enough to increase the ambient relative humidity to 100%. Therefore smoke moisture may be a contributing factor to the location and timing of fog formation.

scholarly journals Volatile Organic Compound Analysis by Sorbent Tube-Thermal Desorption-Gas Chromatography: A Review

2018 ◽  
Vol 7 (3.14) ◽  
pp. 165
Author(s):  
Md Firoz Khan ◽  
Mazrura Sahani ◽  
Mohd Shahrul Mohd Nadzir ◽  
Lin Chin Yik ◽  
Hossain Mohammad Syedul Hoque ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Urban Areas ◽  
Ground Level ◽  
Ambient Air ◽  
Careful Consideration ◽  
Northeast Monsoon ◽  
Oxides Of Nitrogen ◽  
Ozone Pollution ◽  
Photochemical Pollution ◽  
Volatile Organic

Volatile organic compounds (VOCs) play an important role in the generation of ground level ozone and secondary organic aerosol. Most tropical countries such as Malaysia, Singapore, Indonesia, Brunei experience high ozone pollution. Beside ozone, oxides of nitrogen (NOx) from vehicular emissions also play an important role in photochemical pollution. NOx, particularly nitric oxide (NO), helps to ‘clean up’ ozone concentrations close to traffic in the ambient air of urban areas. Thus, knowledge of the chemistry of ozone-VOCs-NOx and finding the sources of VOCs are crucial to proceed with an appropriate mitigation strategy. Thus, the detection of ozone precursors and related VOCs is thoroughly discussed. This review finds that the inertness, hydrophobicity, and the effect of the artefact materials are very significant factors to be explored in the selection of the sorbent materials. In the SEA region, relative humidity is relatively high and exceeds 90% during the northeast monsoon. Thus, the hydrophobic properties of the sampling material need careful consideration. Further to the effect of relative humidity (RH), the artefact effect of the material itself is a challenge to be optimized and multi-sorbent material in a single tube could be a viable choice to minimize the effect of the unwanted signal in the spectrum.     

Fluid Properties at Gas Turbine Inlet Due to Fogging Considering Evaporation and Condensation Phenomena as Well as Icing Risk

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Christoph Günther ◽  
Franz Joos
Keyword(s):  
Relative Humidity ◽  
Gas Turbine ◽  
Ambient Air ◽  
Equilibrium Conditions ◽  
Evaporation And Condensation ◽  
The Third ◽  
Ambient Relative Humidity ◽  
Fluid Properties ◽  
Nonequilibrium Conditions ◽  
Gas Turbine Compressor

This study reports on numerically calculated thermophysical properties of air entering a gas turbine compressor after passing through an intake duct affected by different cooling techniques. Case of reference is unaffected ambient air (referenced to as unaffected) passing the intake duct. Furthermore, ambient air cooled down to wet bulb temperature by (overspray) fogging (referenced to as wet) was considered. The third case shows air cooled down to the same temperature as it was reached in the wet case but by using chillers (referenced to as chilled). Equilibrium and nonequilibrium properties according to the occurring evaporation and condensation phenomena were compared. Equilibrium conditions seem to have a reduced inlet icing risk for the wet case compared to the chilled case. However, comparing the wet case to the unaffected case showed a higher icing risk for the wet case at low ambient relative humidity. In contrast to equilibrium conditions, a consideration of nonequilibrium conditions resulted in an increased icing risk due to almost negligible condensation rates.

CATFISH DRYING (Clarias Batraclus) USING ‘TEKO BERSAYAP’ SOLAR DRYER

2012 ◽  
Vol 2 (1) ◽  
pp. 14-20
Author(s):  
Yuwana Yuwana
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Ambient Temperature ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Time ◽  
Ambient Relative Humidity ◽  
Solar Dryer

Experiment on catfish drying employing ‘Teko Bersayap’ solar dryer was conducted. The result of the experiment indicated that the dryer was able to increase ambient temperature up to 44% and decrease ambient relative humidity up to 103%. Fish drying process followed equations : KAu = 74,94 e-0,03t for unsplitted fish and KAb = 79,25 e-0,09t for splitted fish, where KAu = moisture content of unsplitted fish (%), KAb = moisture content of splitted fish (%), t = drying time. Drying of unsplitted fish finished in 43.995 hours while drying of split fish completed in 15.29 hours. Splitting the fish increased 2,877 times drying rate.

scholarly journals A 3D study on the amplification of regional haze and particle growth by local emissions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Wei Du ◽  
Lubna Dada ◽  
Jian Zhao ◽  
Xueshun Chen ◽  
Kaspar R. Daellenbach ◽  
...  
Keyword(s):  
Atmospheric Stability ◽  
Ground Level ◽  
Particle Growth ◽  
Chemical Compositions ◽  
Size Distributions ◽  
Aerosol Composition ◽  
Regional Haze ◽  
Haze Formation ◽  
Beijing China

AbstractThe role of new particle formation (NPF) events and their contribution to haze formation through subsequent growth in polluted megacities is still controversial. To improve the understanding of the sources, meteorological conditions, and chemistry behind air pollution, we performed simultaneous measurements of aerosol composition and particle number size distributions at ground level and at 260 m in central Beijing, China, during a total of 4 months in 2015–2017. Our measurements show a pronounced decoupling of gas-to-particle conversion between the two heights, leading to different haze processes in terms of particle size distributions and chemical compositions. The development of haze was initiated by the growth of freshly formed particles at both heights, whereas the more severe haze at ground level was connected directly to local primary particles and gaseous precursors leading to higher particle growth rates. The particle growth creates a feedback loop, in which a further development of haze increases the atmospheric stability, which in turn strengthens the persisting apparent decoupling between the two heights and increases the severity of haze at ground level. Moreover, we complemented our field observations with model analyses, which suggest that the growth of NPF-originated particles accounted up to ∼60% of the accumulation mode particles in the Beijing–Tianjin–Hebei area during haze conditions. The results suggest that a reduction in anthropogenic gaseous precursors, suppressing particle growth, is a critical step for alleviating haze although the number concentration of freshly formed particles (3–40 nm) via NPF does not reduce after emission controls.

scholarly journals Winter Ozone Pollution in Utah’s Uinta Basin is Attenuating

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 4
Author(s):  
Marc L. Mansfield ◽  
Seth N. Lyman
Keyword(s):  
Ground Level ◽  
Ambient Air ◽  
Quality Standard ◽  
Ozone Pollution ◽  
Uinta Basin ◽  
Concentration Data ◽  
Previous Decade ◽  
High Concentrations ◽  
Ambient Air Quality Standard ◽  
Ozone Precursor

High concentrations of ground-level ozone have been observed during wintertime in the Uinta Basin of western Utah, USA, beginning in 2010. We analyze existing ozone and ozone precursor concentration data from 38 sites over 11 winter seasons and conclude that there has been a statistically significant (p < 0.02) decline in ozone concentration over the previous decade. Daily exceedances of the National Ambient Air Quality Standard for ozone (70 ppb) have been trending downward at the rate of nearly four per year. Ozone and NOx concentrations have been trending downward at the rates of about 3 and 0.3 ppb per year, respectively. Concentrations of organics in 2018 were at about 30% of their values in 2012 or 2013. Several markers, annual ozone exceedance counts and median ozone and NOx concentrations, were at their largest values in the period 2010 to 2013 and have never recovered since then. We attribute the decline to (1) weakening global demand for oil and natural gas and (2) more stringent pollution regulations and controls, both of which have occurred over the previous decade. We also see evidence of ozone titration when snow cover is absent.

scholarly journals Prioritizing and Analyzing the Role of Climate and Urban Parameters in the Confirmed Cases of COVID-19 Based on Artificial Intelligence Applications

2020 ◽  
Vol 17 (10) ◽  
pp. 3730 ◽  
Author(s):  
Sina Shaffiee Haghshenas ◽  
Behrouz Pirouz ◽  
Sami Shaffiee Haghshenas ◽  
Behzad Pirouz ◽  
Patrizia Piro ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Infectious Disease ◽  
Relative Humidity ◽  
Cost Function ◽  
Selection Process ◽  
Environmental Parameters ◽  
Pso Algorithm ◽  
Data Set ◽  
De Algorithm

Nowadays, an infectious disease outbreak is considered one of the most destructive effects in the sustainable development process. The outbreak of new coronavirus (COVID-19) as an infectious disease showed that it has undesirable social, environmental, and economic impacts, and leads to serious challenges and threats. Additionally, investigating the prioritization parameters is of vital importance to reducing the negative impacts of this global crisis. Hence, the main aim of this study is to prioritize and analyze the role of certain environmental parameters. For this purpose, four cities in Italy were selected as a case study and some notable climate parameters—such as daily average temperature, relative humidity, wind speed—and an urban parameter, population density, were considered as input data set, with confirmed cases of COVID-19 being the output dataset. In this paper, two artificial intelligence techniques, including an artificial neural network (ANN) based on particle swarm optimization (PSO) algorithm and differential evolution (DE) algorithm, were used for prioritizing climate and urban parameters. The analysis is based on the feature selection process and then the obtained results from the proposed models compared to select the best one. Finally, the difference in cost function was about 0.0001 between the performances of the two models, hence, the two methods were not different in cost function, however, ANN-PSO was found to be better, because it reached to the desired precision level in lesser iterations than ANN-DE. In addition, the priority of two variables, urban parameter, and relative humidity, were the highest to predict the confirmed cases of COVID-19.

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