Dew formation characteristics of meadow plants canopy at different heights in Hulunbuir grassland, China

A plant's foliar uptake of dew can mitigate the adverse effects caused by drought stress. However, in grassland ecosystems, it is inconclusive whether the dew condensation characteristics of plants at different heights are consistent. In this study, we wanted to know whether plant height had a significant effect on the formation of dew. In addition, we wanted to understand the difference of dew formation between C3 plant Leymus chinensis (LC) and C4 plant Cleistogenes squarrosa (CS) which have different heights and can succeed each other in the community. In nine dew nights, we measured the amount of dew formed on simulated condensation surface (different heights) and two plants at the same time. The results showed that in the height range of 5–80 cm, the dew amount increases with the canopy height, but its increase rate gradually slows down and approaches zero. The shorter CS (5–15 cm) has a similar dew amount (0.095 mm) as LC (40–70 cm) due to its compact structure of the leaves with pubescence and the more stable micro-meteorological conditions. The CS can obtain more potential dew per unit organic matter, and this may be one of the potential mechanisms for the succession from LC communities to CS communities under drought stress.

Infrared heater warming system markedly reduces dew formation: An overlooked factor in arid ecosystems

ABSTRACTDew plays a vital role in ecosystem processes in arid and semi-arid regions and is expected to be affected by climate warming. Infrared heater warming systems have been widely used to simulate climate warming effects on ecosystem. However, how this warming system affects dew formation has been long ignored and rarely addressed. In a typical alpine grassland ecosystem on the Northeast of the Tibetan Plateau, we measured dew amount and duration by artificial condensing surfaces, leaf wetness sensors and in situ dew formation on plants from 2012 to 2017. We also measured plant traits related to dew conditions. The results showed that (1) warming reduced the dew amount by 41.6%-91.1% depending on the measurement method, and reduced dew duration by 32.1 days compared to the ambient condition. (2) Different plant functional groups differed in dew formation. (3) Under the infrared warming treatment, the dew amount decreased with plant height, while under the ambient conditions, the dew amount showed the opposite trend. We concluded that warming with an infrared heater system greatly reduces dew formation, and if ignored, it may lead to overestimation of the effects of climate warming on ecosystem processes in climate change simulation studies.

Dew condensation during a typical haze event in Changchun, China

Haze is one of the most serious environmental problems affecting China. This study monitored the changes in dew amount and quality during a haze event that occurred in 2016. Water vapor migrated continuously to the near surface during the haze event. The period of dew condensation increased because of meteorological factors, and the daily dew amount (0.178 mm) was higher during the haze event than in non-haze weather (0.0607 mm). The concentrations of all ions in the dew increased gradually during the haze event, peaking during the most serious period of the haze. The concentrations of SO42− and NH4+ reached 15,325.95 and 13,865.45 μeq/L, which were 2.24 and 10.83 times greater than those obtained before the haze event, respectively. During the haze event, the particulate matter (PM) concentrations within the dew increased, and the mass concentrations of PM2.5 and PM2.5-10 during the worst haze event were 65.3 and 166.1 mg/L, respectively. The dew mainly removed coarse PM; the average removal rates of PM2.5 and PM2.5-10 during the haze event were 13.6% and 16.9%, respectively. Dew can capture PM throughout a haze event, and its purifying effect on the underlying surface was obvious, especially during the beginning of the event.

The Effect of Climate Change on Variations in Dew Amount in a Paddy Ecosystem of the Sanjiang Plain, China

Due to global warming, a drying and warming trend has been observed over the last 50 years in the Sanjiang Plain of Heilongjiang Province, China, which could significantly affect the condensation of vapor in paddy ecosystems. Dew is a crucial factor in the water and nutrient cycling of farmland ecosystems, and it exerts an important influence on fertilization and other agricultural activities. In order to reveal the effects of global warming on dew variation in a paddy ecosystem, anin situexperiment was conducted in paddy fields in the Sanjiang Plain during the growing seasons of 2011 to 2013. Dew was collected and measured with a poplar stick. The results of correlation analysis between meteorological factors and dew intensity in the paddy ecosystem indicate that the dew point temperature and relative humidity significantly influenced the dew intensity. Based on synchronous meteorological data, a stepwise linear multivariation regression model was established to predict dew amount. The model successfully interpreted the relationship between simulated and measured dew intensity. The results suggest that a warmer and drier climate would lead to a reduction in dew amount because water cannot condense when relative humidity falls below 71%.

Meteorological Factors Affected Dew Condensation in Marsh Ecosystem

Dew is one of crucial factors in the water and nutrient cycle in wetland ecosystem, especially playing an important role in the water and nutrients balance. Identifying the meteorological factors which affect the formation of dew is necessary. The meteorological condition is the key factor of dew condensing; therefore, it is necessary to identify the relationship between meteorological factors and dew formation. Dew amount was monitored and collected in the Sanjiang Plain. The highest mean dew amounts at Sanjiang Plain were observed in Craex lasiocarpa community (0.130mm night-1). Nearly 50% dew events correspond to the smallest yields (<0.04 mm="" night="" sup="">-1) and it is implies there are around half days are unsuitable for dew condensation in Craex lasiocarpa community. Our study impies that dew data, taken in growthing season of 2003 to 2005 and 2008, correlated positive with relative humidity, dew point temperature, and vapour pressure.

Dew Amount in Marsh Monitoring in the Sanjiang Plain

Dew is the condensation of atmospheric moisture on objects that have radiated sufficient heat to lower their temperature below the dew point temperature. Dew amount was collected by woodstick in Craex lasiocarpa which the main community at Sanjiang Plain. The average daily cumulated dew yield, which is the important parameter for dew harvesting, reach the peak in August or September. The result implies there are around one fifth days are unsuitable for dew condensation. Dew amount correlated negatively with wind speed.

Harvesting Dew with Radiation Cooled Condensers to Supplement Drinking Water Supply in Semi-arid

This paper describes the development of dew harvest systems for use in semi-arid coastal region of north-west India, chronically short of drinking water. These were developed to ameliorate drinking water problem, especially of people living near the coast where groundwater is of poor quality and surface sources scarce. Although dew is much smaller in magnitude (20-30 mm) than the rains (300 mm) it is a more reliable source. Dew occurs over a season of seven months (October to April), rain over four (June - September). Dew nights number ~ 100, rainy days 15-20. There is much greater year to year variation in rainfall than in the dew amount. A R&D program of over four years led to development of three types of systems - condenser-on-roof (CoR), condenser-on-ground (CoG) and Roof-as-Condenser (RaC). The CoR, CoGs employ condenser made of plastic film insulated on the underside. CoRs are constructed over the roof of buildings, CoGs on open ground. The RaCs use metal roof of buildings itself as condenser. The CoR and CoGs give higher output, require higher investment. The RaCs give lower output; require only a small investment in collection and storage. Examples of working installation are presented. Rain and dew seasons in the region are complementary. Although engineered specifically to harvest dew, these also harvest rain, providing varying amounts of potable water through the year. Benefits to the region, learning accrued and partnerships created in the course of work are also briefly discussed.