Rise In Humidity Research Articles

Analysis of meteorological factors on different stages of heavy haze pollution in Beijing, 2019

. Beijing occurred severe haze events in winter of recent years. To understand the extreme events, the air pollution case from 9 January to 15 January 2019 was selected. The PM2.5concentration of 34 monitoring sites which were hourly measured, the nationwide synoptic conditions at surface and 850hpa, the meteorological factors including temperature, wind speed and humidity and the vertical variation in Planetary boundary layer (PBL) during the case were analyzed. It is found that synoptic condition, meteorological factors and urban PM2.5(fine particles with diameter less than 2.5μm) concentration distribution changed regularly with time. Clean stage, transport stage, cumulative stage and dispersion stage during haze are defined in this study. Three overall research results are: (1) The synoptic variation is distinct. Beijing is alternately dominated by Siberian High-pressure and Western Pacific Subtropical High-pressure system in winter. The transport stage is with predominant Subtropical High-pressure which brings temperature and humidity rise. High humidity facilitates formation of secondary aerosols. The cumulative stage ends along with boosted Siberian High-pressure. (2) The severe haze is characterized by temperature inversion, low wind speed and high humidity, especially nearby surface, and experienced PM2.5explosive growth. The stability of PBL structure will be strengthened with decreased PBL height, which inhibits the dispersion of pollutants. (3) The PM2.5concentrations during different stages had different regional distribution. The southern PM2.5concentration is much high than northern in transport stage. During dispersion stage, urban central PM2.5is the high for the reason that buildings, vehicle exhaust and urban heat island effects all impedehaze disappearing.

Multi-responsive red solid emitter: Detection of trace water and sense of relative humidity

A multi-responsive D-A type compound ( CYQ ) based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission (AEE) effect. Solvatochromic experiment and density functional theory (DFT) indicated CYQ possessed excellent intramolecular charge transfer (ICT) ability. Besides, its mechanofluorochromic property (MFC) was found with a 37 nm red-shift. Powder wide-angle X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly, CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran (THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity (RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.

Laser Direct Writing of a High-Performance All-Graphene Humidity Sensor Working in a Novel Sensing Mode for Portable Electronics.

This paper reports a fast and highly sensitive all-graphene humidity sensor working in a novel alternating current (ac) detection mode for the first time, which is capable of sensing humidity on a smartphone for portable electronics. The humidity sensor is based on an interdigitated reduced graphene oxide/graphene oxide/rGO (rGO/GO/rGO) structure patterned by a facile laser direct writing method. It works in an ac sensing mode with a rectangular input voltage wave and measurestheoutput voltage wave instead of conventional resistance, impedance, or capacitance, exhibiting a dramatically enhanced sensitivity by about 45 times compared to the low and unstable response in dc mode. The humidity sensor shows an obvious response to the relative humidity (RH) ranging from RH 6.3% to RH 100%. The response and recovery toward humidity change are almost instantaneous, and the corresponding costed times including humidity rise and decay times are less than 1.9 and 3.9 s, respectively, which are among the best results in the literature. The sensor also exhibits outstanding cycling stability, flexibility, and long-term stability (>1 year), as well as good reproducibility of device preparation. Besides, it can be easily connected to an iPhone and the humidity sensing can be conducted with an oscilloscope application on iOS. What's more, an electronic circuit simulation method was employed to fit the output waves, which can not only explain the sensing mechanism, but also determine the resistance and capacitance of the rGO/GO/rGO structure, agreeing well with the results obtained from the electrochemical measurements. It can be reasonably expected that the approach combining humidity sensing and electronic circuit simulation can be applied in real-time monitoring on a smartphone based on the Internet of things and big data technologies.

Humid heat and climate change

Extreme heat events cause significant societal impacts, prompting much concern and research about possible changes to their frequency and intensity as the climate warms. However, to date, extremes in air temperature have been emphasised at the expense of ‘heat-humidity’ indices, measures which incorporate the effect of atmospheric latent heat content on heat stress and provide a more complete picture of the thermal environment for human thermoregulation. This progress report restores balance by reviewing recent developments in the understanding of how heat-humidity indices have changed, and may continue to, as the climate warms further. The literature indicates that a concurrent rise in temperature and absolute humidity has already increased the frequency of potentially deadly conditions, and has reduced labour potential worldwide. More serious consequences may result if mitigation efforts are unsuccessful. The energetic basis of a heat-humidity perspective has permitted researchers to identify, for example, that by the end of the century, substantial parts of the Earth’s surface may be too hot and humid for human thermoregulation. Such consequences are avoided for less pessimistic scenarios of climate warming, but the societal impacts may still be very severe, as densely-populated low-latitude environments emerge as particularly at risk when a humid heat perspective is adopted. Counter to air temperature, changes in mean heat-humidity indices are actually amongst the largest worldwide at lower latitudes, where only small increases in the mean may be required to substantially enhance the frequency of dangerous conditions. The report concludes by outlining areas requiring improved process understanding, and it highlights the urgent role for societal adaptation if the worst impacts from rising humid heat are to be avoided.

An update on recent glacier changes in Mexico using Sentinel-2A data

ABSTRACTThis study estimated the recent evolution of three glacierized stratovolcanoes – namely Volcán Iztaccíhuatl, Volcán Popocatépetl and Volcán Citlaltépetl – in South-central Mexico using Landsat and Sentinel-2A satellite data acquired between 1973 and 2017. These three glaciers are influenced by various factors such as climate change, volcanic eruption and pollution. Three key climate variables, which control the presence of glacier coverage – air temperature, precipitation and humidity – were also analysed. Among these three volcanoes, only Volcán Iztaccíhuatl and Volcán Citlaltépetl have ice-covered areas since the late 1990s and Volcán Popocatépetl has lost its glaciers due to volcanic eruption, even though the glacier shrinkage has started long before the appearance of eruptive products. An overall glacier area loss of 75% has been observed for the period between 1973 and 2017. Shrinkage of Volcán Citlaltépetl (66%) is comparable with the retreat observed in the tropical Andes of Peru and Bolivia during the same period. Observed trends in the air temperature were not very significant for all the three glaciers studied whereas a substantial rise in relative humidity (+0.11%/year) was observed. Trends in precipitation were different for Citlaltépetl (+7.8 mm/year) and the other two volcano-glaciers (−5.1 mm/year).

Comparative Study of Transpiration in Cooling Effect of Tree Species in the Atmosphere

Trees create microclimate under their crowns in comparison to the outside ambient atmosphere, which is a result of physical as well as physiological functions of the tree. The cooling produced by trees varies with species due to variation in several anatomical, structural and physiological attributes of the species. Transpiration is one of the most significant physiological functions performed by plants, which affects cooling produced by a tree under its shade. When solar energy impinges on the leaf, water emerges from its surface through transpiration taking the latent heat to convert it into water vapour. This leads to a rise in humidity of the atmosphere and reduction in temperature of the leaf. To remain leaf in equilibrium, it takes heat from the surrounding atmosphere resulting in reduction in temperature of surroundings. Since, transpiration takes place through stomata which are normally located on the ventral side of the leaf, this reduction in temperature is more experienced beneath the crown of the tree. Therefore, the present study was carried out to analyze the role of transpiration in cooling effect of five forestry tree species. The cooling produced by tree species under their shades has been found positively correlated to the transpiration rate whereas the rate of transpiration has responded positively to the ambient temperature and water conductance. However, no definite relationship has been found between frequency of open stomata and the rate of transpiration.

The role of ambient temperature variation on drying shrinkage development of self-compacting Portland-limestone cement concrete

The ambient temperature records in Iraq show a large variation between day and night reaching 20 C, depending on the season, whether it is summer or winter. For this reason, the aim of this research is to study the effect of these conditions on the drying shrinkage of self-compacting concrete produced by using Portland-Limestone cement (ASTM C595 - Type IL). SCC mixes were designed to attain compressive strengths of 40 and 60MPa at 28days with and without silica fume respectively. Same mixes were reproduced with ordinary Portland cement (ASTM C150 - Type I) for comparisons. Two maximum sizes of aggregate 10 and 20 mm were incorporated in this work. The drying shrinkage was measured for 180 days after 7 days of water curing. The range of ambient (outdoor) temperature variation was from - 4 to + 39°C and the relative humidity ranged from 15 to 60 %. The results of this exposure were compared to that of specimens kept in the shrinkage chamber, with a temperature of 21°C and relative humidity 35%. The current results showed that due to the irreversible nature of shrinkage strain, the drop of ambient temperature and the rise of atmosphere moisture or relative humidity would not reverse the shrinkage strain. It is important to figure the final total accumulated strain when dealing with ambient temperature variation. The drying shrinkage characteristics for concrete made with Type IL cement, are found similar to that for concrete produced with Type I cement.

A study of tea leaves drying using dehumidification process and regeneration of liquid desiccant in a closed-cycle dehumidification-humidification

Tea plants in Indonesia are derived from Carmelia sinensis var. assamica which contain catechin in quite high amount compared with other countries tea plant. Green tea is made by inactivating the oxidase / phenolase enzyme that presents in the fresh tea leaf buds from tea garden, by using hot steam to prevent the oxidation of the catechins. Drying process to reduce the moisture of tea, one of the method is by utilizing the dry air from dehumidification process. Liquid desiccant made from 50% concentration of CaCl2, the temperature is lowered to 10 °C and sprayed into the air stream which contains water vapor by using a 0.2 mm spraying nozzle so that mass transfer and latent heat occur in the dehumidifier. The result of air dehumidification process used for drying tea leaves. The air is able to dry the tea leaves from the weight of 58 grams to 47 grams. Then the liquid desiccant dehumidification process will be streamed into the humidifier, where the liquid desiccant regeneration process will have change into the initial concentration. The result of air humidification process has an average absolute humidity rise of 0.07 g/kg. The liquid desiccant regeneration process that happened continuously reaching the saturation point at 280 minutes. It can be concluded that the process of dehumidification-humidification is a fairly effective method for drying the tea leaves.

Increasing air humidity influences hydraulic efficiency but not functional vulnerability of xylem in hybrid aspen

Climate models predict greater increases in the frequency than in the amount of precipitation and a consequent rise in atmospheric humidity at high latitudes by the end of the century. We investigated the responses of hydraulic and relevant anatomical traits of xylem to elevated relative humidity of air on a 1-yr-old coppice of hybrid aspen (Populus×wettsteinii) growing in the experimental stand at the Free Air Humidity Manipulation site in Eastern Estonia. The hydraulic conductivity of stems was measured with a high pressure flow meter; artificial cavitation in the stem segments was induced by the air injection method. Specific conductivity of xylem decreased from 4.42 in the control to 3.94kgm−1s−1MPa−1 in the humidification treatment, while the trend was well correlated with increasing wood density. Humidified trees exhibited smaller leaf area at the same xylem cross-sectional area, resulting in 34% higher average Huber values compared to the control. Control and humidity-treated trees differed by neither native embolism level nor susceptibility to dehydration-induced cavitation. Increasing atmospheric humidity reduces the hydraulic efficiency of hybrid aspen trees expressed on a xylem area basis and causes substantial changes in resource allocation between photosynthetic and water transport tissues. This climate trend does not influence stem vulnerability to cavitation.

Spatiotemporal risk mapping of hand, foot and mouth disease and its association with meteorological variables in children under 5 years.

Hand, foot and mouth disease (HFMD) risk has become an increasing concern in the Beijing-Tianjin-Hebei region, which is the biggest urban agglomeration in north-eastern Asia. In the study, spatiotemporal epidemiological features of HFMD were analysed, and a Bayesian space-time hierarchy model was used to detect local spatial relative risk (RR) and to assess the effect of meteorological factors. From 2009 to 2013, there was an obvious seasonal pattern of HFMD risk. The highest risk period was in the summer, with an average monthly incidence of 4·17/103, whereas the index in wintertime was 0·16/103. Meteorological variables influenced temporal changes in HFMD. A 1 °C rise in air temperature was associated with an 11·5% increase in HFMD (corresponding RR 1·122). A 1% rise in relative humidity was related to a 9·51% increase in the number of HFMD cases (corresponding RR 1·100). A 1 hPa increment in air pressure was related to a 0·11% decrease in HFMD (corresponding RR 0·999). A 1 h increase in sunshine was associated with a 0·28% rise in HFMD cases (corresponding RR 1·003). A 1 m/s rise in wind speed was related to a 6·2% increase in HFMD (corresponding RR 1·064). High-risk areas were mainly large cities, such as Beijing, Tianjin, Shijiazhuang and their neighbouring areas. These findings can contribute to risk control and implementation of disease-prevention policies.

Impact of high daytime air humidity on nutrient uptake and night-time water flux in silver birch, a boreal forest tree species

At northern latitudes, a rise in atmospheric humidity and precipitation is predicted as a consequence of global climate change. We investigated the impact of high (H) and moderate (M) daytime air relative humidity (RH) on water relation parameters and foliar nutrient status in saplings of silver birch, to elucidate the interactions between water and nutrient uptake. A ~40% lower daytime vapour pressure difference between the leaf interior and atmosphere caused significantly (P 0.05) between the treatments. Our results suggest that the 32.3% higher total foliar P in the H treatment could be partly induced by 28.2% greater transpiration-driven mass flow of water-soluble P and/or by 25.4% higher number of absorptive root tips. Our results confirm that elevated daytime atmospheric humidity increases the potential for night-time water flux and might also facilitate the uptake of mineral nutrients in silver birch, a dominating deciduous tree species in boreal forests.

QCMを用いたCO<sub>2</sub>センサの温湿度特性

Temperature and humidity characteristics of a QCM coated with acrylonitrile styrene copolymer (AS) were studied as a CO2 sensor. Consequently, the following results were obtained. 1) A frequency shift of the QCM is in proportion to CO2 concentration under the condition of constant temperature. 2) The sensitivity for CO2 concentration decreases in a linear fashion with a rise in temperature. 3) The frequency shift increases in a parabolic fashion and the sensitivity for humidity increases in a linear fashion with a rise in humidity under the condition of constant temperature. 4) The sensitivity for absolute humidity decreases in a parabolic fashion with a rise in temperature under the condition of constant absolute humidity.

Predicting the severity of Spodoptera litura on groundnut in relation to climatic variability using ordinal logistic model

In this paper, an ordinal logistic regression model was developed for predicting the severity of tobacco caterpillar, Spodoptera litura (Fabricius) on groundnut using the pest dynamics vis a vis climatic data of twenty five years (1990-2014) pertaining to Kharif (26 to 44 standard meteorological weeks (SMW)) season of Dharwad (Karnataka). Trend analysis of climatic data using Mann-Kendall nonparametric test showed that mean and minimum temperatures, and rainfall to be increasing while morning and evening relative humidity and their mean to be decreasing over time. The weekly male moth catches of S. litura (nos./trap/week) during maximum severity period (34 SMW) was modeled with climatic variables lagged by two weeks. The developed model indicated that the maximum temperature and morning relative humidity prior to two weeks contributed significantly to the occurrence of high level of pest attack. Results suggested that for each degree increase in maximum temperature during 32 SMW, the odds of being high pest attack (as opposed to lower or medium) increased by a multiple of 8.6 as compared to the odds of being high or medium (as opposed to low) increasing by 6.4 times for each per cent rise in the morning relative humidity.

Spontaneous wrinkling of layer-by-layer assembled polyelectrolyte films for humidity-responsive superhydrophobicity

The fabrication of smart films with reversible wettability enabled by the stimulus-induced morphology changes has attracted growing interest but remains a challenge. Here we report a smart film that can reversibly changes its wettability between transparent hydrophobicity to translucent superhydrophobicity through the humidity-induced wrinkling/de-wrinkling process. The film was fabricated by depositing hydrophobic SiO2 nanoparticles (NPs) on poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) films, followed by partially exfoliating the films from the underlying substrates. The partially exfoliated PAA/PAH film can reversibly wrinkle and de-wrinkle when being alternately subjected to humid and dry environments. The deposition of hydrophobic SiO2 NPs on the wrinkling PAA/PAH film does not hinder the humidity-enabled wrin-kling/de-wrinkling ability of the composite film. The hydrophobic SiO2 NPs and the underlying humidity-wrinkling PAA/PAH film enable the composite film to spontaneously change from hydrophobic and transparent to superhydrophobic and translucent with the rise of environmental humidity.

A climate-based prediction model in the high-risk clusters of the Mekong Delta region, Vietnam: towards improving dengue prevention and control.

To develop a prediction score scheme useful for prevention practitioners and authorities to implement dengue preparedness and controls in the Mekong Delta region (MDR). We applied a spatial scan statistic to identify high-risk dengue clusters in the MDR and used generalised linear-distributed lag models to examine climate-dengue associations using dengue case records and meteorological data from 2003 to 2013. The significant predictors were collapsed into categorical scales, and the β-coefficients of predictors were converted to prediction scores. The score scheme was validated for predicting dengue outbreaks using ROC analysis. The north-eastern MDR was identified as the high-risk cluster. A 1°C increase in temperature at lag 1-4 and 5-8weeks increased the dengue risk 11% (95% CI, 9-13) and 7% (95% CI, 6-8), respectively. A 1% rise in humidity increased dengue risk 0.9% (95% CI, 0.2-1.4) at lag 1-4 and 0.8% (95% CI, 0.2-1.4) at lag 5-8weeks. Similarly, a 1-mm increase in rainfall increased dengue risk 0.1% (95% CI, 0.05-0.16) at lag 1-4 and 0.11% (95% CI, 0.07-0.16) at lag 5-8weeks. The predicted scores performed with high accuracy in diagnosing the dengue outbreaks (96.3%). This study demonstrates the potential usefulness of a dengue prediction score scheme derived from complex statistical models for high-risk dengue clusters. We recommend a further study to examine the possibility of incorporating such a score scheme into the dengue early warning system in similar climate settings.

Alternate mild drought stress (−0.1 MPa PEG) immunizes sensitive chickpea cultivar against lethal chilling by accentuating the defense mechanisms

The changes in climate particularly, the rise in temperature and humidity affect the physiological functions of plants subsequently affecting crop productivity adversely. A strategy is required which can be directly implemented in fields to induce the tolerance in crop plants. In present study, two chickpea varieties with contrasting sensitivity PDG3 (Tolerant) and GPF2 (Sensitive) were raised hydroponically, preconditioned with mild drought stress (0.1 MPa PEG-6000) for 3 days (above 0.1 MPa is lethal) and subsequently recovered for double time (6 days) and finally exposed to lethal cold stress (4 °C) for 3 days. We hypothesize that preconditioning with non-lethal drought stress may immunize the plants to combat lethal cold stress. Membrane integrity improved in root and shoot, lipid peroxidation decreased to control level in preconditioned seedlings. Cellular respiration ability (% TTC reduction) increased in the preconditioned seedlings to almost 90 % in the shoot and 60 % in the root, concurrently it was 45 % in non-preconditioned seedlings. Proline content also increased in preconditioned seedlings, especially roots. Carbohydrate had a shift in terms of a high amount of total, reducing sugars and starch in non-preconditioned seedlings compared to preconditioned. Both PDG3 and GPF2 showed enhanced SOD, CAT and GPOX activity indicating tolerance against cold-induced oxidative stress and preconditioning induced improvement against lethal cold stress.

An experimental study of ash accumulation in flue gas

Accumulation of small particles is beneficial for dust removal. We have carried out experiments to investigate the influences of flue gas properties, especially temperature, humidity, sulfuric acid, and dust concentrations, on ash particle accumulation. The ash used was collected from an electric precipitator of a coal-fired power station. It is found that ash accumulation is strongly influenced by the flue gas temperature in comparison with the Engineering Acid Dew Temperature (EADT). With decreasing temperature below the EADT, both the sulfuric acid in flue gas and the ash humidity rise, and the collected particles weight and sizes increase. Therefore, the flue gas temperature can be controlled to enhance particle accumulation and improve ash collection efficiency.

Association between the incidence of varicella and meteorological conditions in Jinan, Eastern China, 2012-2014.

BackgroundVaricella remains an important public health issue in China. In this study we explored the effect of weather conditions on the incidence of varicella in the temperate city of Jinan, Eastern China during 2012–2014 to inform public health prevention and control measures.MethodsData on reported cases of varicella were obtained from National Notifiable Disease Report System. Meteorological data for the same time period were obtained from the Jinan Meteorological Bureau. A negative binomial regression model was used to assess the relationships between meteorological variables and the incidence of varicella. Given collinearity between average temperature and atmospheric pressure, separate models were constructed: one including average temperature without atmospheric pressure, the other including atmospheric pressure but without average temperature. Both models included relative humidity, wind velocity, rainfall, sunshine, and year as independent variables.ResultsAnnual incidence rates of varicella were 44.47, 53.69, and 46.81 per 100,000 for 2012, 2013, and 2014, respectively. Each increase of 100 Pa (hPa) in atmospheric pressure was estimated to be associated with an increase in weekly incidence of 3.35 % (95 % CI = 2.94–3.67 %), while a 1 °C rise in temperature was associated with a decrease of 3.44 % (95 % CI = −3.73–3.15 %) in the weekly incidence of varicella. Similarly, a 1 % rise in relative humidity corresponded to a decrease of 0.50 % or 1.00 %, a 1 h rise in sunshine corresponded to an increase of 1.10 % or 0.50 %, and a 1 mm rise in rainfall corresponded to an increase of 0.20 % or 0.30 %, in the weekly incidence of varicella cases, depending on the variable considered in the model.ConclusionOur findings show that weather factors have a significant influence on the incidence of varicella. Meteorological conditions should be considered as important predictors of varicella incidence in Jinan, Eastern China.

Palaeoenvironmental change in Southern Patagonia during the Lateglacial and Holocene: Implications for forest refugia and climate reconstructions

A high-resolution palynological record from Punta Yartou, Fuego-Patagonia (53°51′S; 70°08′W), supported by lithostratigraphy, radiocarbon dating and tephrochronology, was examined to reconstruct the vegetation changes during the last glacial–interglacial transition and the Holocene. Following deglaciation from the Last Glacial Maximum sometime before c. 23,070 Cal yr BP the vegetation was initially dominated by Ericaceous shrubs and following modest climate amelioration between c. 20,480 and 14,820 Cal yr BP the environment favoured the spread of Acaena. The trend to a warmer and more humid climate was interrupted between c. 14,820 and 13,560 Cal yr BP when the vegetation community was dominated by cold tolerant herbs such as Poaceae and Asteraceae (Subfamily Asteroideae), suggesting an open treeless landscape with colder climatic conditions coeval with the Antarctic Cold Reversal. After c. 13,560 Cal yr BP a gradual rise in temperature and humidity is inferred from the colonisation of Nothofagus. A further warming and increase is inferred from the establishment of the forest/steppe ecotone by c. 12,900 Cal yr BP. The early Holocene was then characterised by increasing development of Nothofagus open canopy forest. However, between c. 8080 and 5060 Cal yr BP there was a significant reduction in the forest cover and high values of charcoal which suggest an intense arid phase leading to increased availability of dry fuel. Between c. 5060 and 2170 Cal yr BP there were centennial-scale periods of increased wetter and colder climatic conditions. The Punta Yartou record demonstrates the sensitivity of Fuego-Patagonian forest to changes in the proximity and intensity of the southern westerly winds.

Extinction risks and conservation status of Corybas (Orchidaceae; Orchidoideae; Diurideae) in Peninsular Malaysia

Corybas is an elusive terrestrial orchid genus mostly inhabiting the high peaks in Peninsular Malaysia, which is the most vulnerable habitat to climate change. Nine species, of which seven are endemic, were studied based on natural populations, whereas information on another two was obtained from herbarium collections. Corybas caudatus was excluded from the study due to insufficient materials, and the type was not located. The species investigated were growing in small populations in the remaining moss-covered forests in the highlands. Human activities and temperature rise are two major threats to the wild populations. Our field observations revealed that Corybas species are good indicators of climate change as they are highly sensitive to temperature rise and drop in relative humidity. Judging from the current small number of specimens recollected, the small population sizes and degraded habitats where they grow, Corybas species in Peninsular Malaysia are all threatened by extinction in the wild.