Decrease In Relative Humidity Research Articles

An example of the analysis of climate change in agriculture using Griffiths-Taylor diagrams

The climate clearly determines the characteristics of agriculture in terms of favourable conditions for the development of plants and animals. Climate change has a major impact on agriculture, and we need at least its analysis for past decades for effective adaptation. The annual scale of meteorological variables is quite rough, much more information is obtained from the monthly scale, for example when using bioclimatic indices and diagrams. Using Griffiths-Taylor diagrams, where each point shows the average monthly value of temperature and relative humidity or precipitation, we showed the change of 30-year averages (1961 to 2020) for six climate stations. Climate change can be seen from the shape of the diagram, an increase in average monthly air temperatures, a decrease in average relative humidity and changed precipitation patterns are visible. With the plot of favourable conditions for a certain plant / animal species, the diagram acquires ecological value. We have shown changes in the conditions for the development of the fruit fly (Ceratitis capitata (Wiedemann, 1824)) and the growth of sweet potatoes (Ipomoea batata L.). For the fruit fly, conditions improved due to higher temperatures, especially in colder locations. In Murska Sobota, which has the only suitable conditions for the growth of sweet potatoes, the period with favourable conditions is extended, in the last two periods in July and August, ideal conditions also appear. In further research, we recommend an analysis of weather-extreme years, which provides additional information on the variability of the conditions.

Impact of COVID-19 lockdown on the atmospheric boundary layer and instability process over Indian region

The abrupt reduction in the human activities during the first lockdown of the COVID-19 pandemic created unprecedented changes in the background atmospheric conditions. Several studies reported the anthropogenic and air quality changes observed during the lockdown. However, no attempts are made to investigate the lockdown effects on the Atmospheric Boundary Layer (ABL) and background instability processes. In this study, we assess the lockdown impacts on the ABL altitude and instability parameters (Convective Available Potential Energy (CAPE) and Convective Inhibition Energy (CINE)) using WRF model simulations. Results showed a unique footprint of COVID-19 lockdown in all these parameters. Increase in the visibility, surface temperature and wind speed and decrease in relative humidity during the lockdown is noticed. However, these responses are not uniform throughout India and are significant in the inland compared to the coastal regions. The spatial variation of temperature (wind speed) and relative humidity shows an increase and decrease over the Indo Gangetic Plain (IGP) and central parts of India by 20% (100%) and 40%, respectively. Increase (80%) in the ABL altitude is larger over the IGP and central parts of India during lockdown of 2020 compared to similar time period in 2015–2019. This increase is attributed to the stronger insolation due to absence of anthropogenic activity and other background conditions. At the same time, CAPE decreased by 98% in the IGP and central parts of India, where it shows an increase in other parts of India. A prominent strengthening of CINE in the IGP and a weakening elsewhere is also noticed. These changes in CAPE and CINE are mainly attributed to the dearth of saturation in lower troposphere levels, which prevented the development of strong adiabatic ascent during the lockdown. These results provide a comprehensive observation and model-based insight for lockdown induced changes in the meteorological and thermo-dynamical parameters.

Visibility, aerosol optical depth, and low-visibility events in Bangkok during the dry season and associated local weather and synoptic patterns.

Visibility and aerosol optical depth (AOD) characterization, and their relationship with PM10 and local and synoptic meteorology, were studied for January-March in 2014 and 2015 over Bangkok. Visibility degradation intensifies in the dry season as compared to the wet season due to increase in PM10 and unfavorable meteorological conditions. The average visibility is lower in January and February as compared to the other months. Relatively higher AOD in March despite lower PM10 is attributed to the synergetic effect of moderate relative humidity, secondary aerosols, elevated aerosol layer due to summertime convection, and biomass burning. Larger variability in visibility and PM10 in winter months is due to more synoptic weather fluctuations while AOD shows similar variability for all months attributed partly to fires. Higher PM10 and moderate-to-high relative humidity cause lower visibility in the morning while it improves in afternoon as PM10 and relative humidity decrease. AOD is higher in the afternoon as compared to that in the morning and evening as it is less sensitive to diurnal change in aerosols and meteorology at the surface level. Visibility and AOD relationships with PM10 are dependent on relative humidity. Weaker winds lead to lower visibility, higher PM10, and higher AOD irrespective of wind direction. Stronger winds improve visibility and decrease PM10 for all directions while AOD is higher for all directions except eastern and northeastern. The back-trajectory results show that the transport of pollutant and moist air is coupled with the synoptic weather and influence visibility and AOD. Two low-visibility events were investigated. The first event is potentially caused by the combined effect of local emissions and their accumulation due to stagnant weather conditions, secondary aerosols, and forest fires in the nearby regions. The second event can be attributed to the local emission and fires in the nearby area with hygroscopic growth of aerosols due to moist air from the Gulf of Thailand. Based on these findings, some policy implications have also been given.

Mount Everest's photogenic weather during the post‐monsoon

Mount Everest's photogenic weather during the post‐monsoon

Seasonally and Diurnally Varying Cold Front Effects along the Minnesotan North Shore of Lake Superior

Cold fronts are typically associated with cooling, drying and a strengthening wind that shifts to have a northerly component. Cold front effects at a particular point, however, are dependent upon pre-existing air mass characteristics. Here, we examine 634 passages of synoptic-scale cold fronts in northeastern Minnesota from 2010 to 2018. While these fronts are associated with the expected effects in some areas, they are often associated with warming and enhanced drying in the region directly influenced by an air mass from Lake Superior (coastal sites). Coastal sites experience warming during more than half of cold frontal passages, in contrast to proximate inland sites out of the influence of the lake. This warming, combined with a removal of the moist lake air mass, often leads to a sharp post-front decrease in relative humidity. These relatively unusual local effects indicate a need to carefully consider characteristics of the lake air mass and likely changes during cold frontal passage when forecasting regional temperature and fire weather conditions.

Behind the Manufacturing of Industrial Clay Bricks: Drying Stage Predictions Using CFD

Drying of ceramic materials plays important role for industry, involving questions related to investments, energy consumption, product quality, and environmental pollution. In this sense, this work aims to predict heat and mass transfer during the drying process of an industrial clay brick in oven. Simulations were carried out by computational fluid dynamics (Ansys CFX software). Results of the drying and heating kinetics and the moisture content and temperature distributions of the product at different elapsed times are shown and analyzed. The results showed a good agreement between the experimental data, of the surface temperature and the average moisture content, and the numerical results. From the results, it was verified that the proposed mathematical modeling was adequate, providing predicted results in accordance with the experimental data used. Furthermore, numerical results showed that an increase in drying-air temperature and a decrease in relative humidity lead to an increase in heating and moisture removal rates. In the research, it was observed that mass diffusion coefficient increased with increasing drying-air temperature.

Effects and Interaction of Meteorological Parameters on Influenza Incidence During 2010-2019 in Lanzhou, China.

BackgroundInfluenza is a seasonal infectious disease, and meteorological parameters critically influence the incidence of influenza. However, the meteorological parameters linked to influenza occurrence in semi-arid areas are not studied in detail. This study aimed to clarify the impact of meteorological parameters on influenza incidence during 2010–2019 in Lanzhou. The results are expected to facilitate the optimization of influenza-related public health policies by the local healthcare departments.MethodsDescriptive data related to influenza incidence and meteorology during 2010–2019 in Lanzhou were analyzed. The exposure-response relationship between the risk of influenza occurrence and meteorological parameters was explored according to the distributed lag no-linear model (DLNM) with Poisson distribution. The response surface model and stratified model were used to estimate the interactive effect between relative humidity (RH) and other meteorological parameters on influenza incidence.ResultsA total of 6701 cases of influenza were reported during 2010–2019. DLNM results showed that the risk of influenza would gradually increase as the weekly mean average ambient temperature (AT), RH, and absolute humidity (AH) decrease at lag 3 weeks when they were lower than 12.16°C, 51.38%, and 5.24 g/m3, respectively. The low Tem (at 5th percentile, P5) had the greatest effect on influenza incidence; the greatest estimated relative risk (RR) was 4.54 (95%CI: 3.19–6.46) at cumulative lag 2 weeks. The largest estimates of RRs for low RH (P5) and AH (P5) were 4.81 (95%CI: 3.82–6.05) and 4.17 (95%CI: 3.30–5.28) at cumulative lag 3 weeks, respectively. An increase in AT by 1°C led to an estimates of percent change (95%CI) of 3.12% (−4.75% to −1.46%) decrease in the weekly influenza case counts in a low RH environment. In addition, RH showed significant interaction with AT and AP on influenza incidence but not with wind speed.ConclusionThis study indicated that low AT, low humidity (RH and AH), and high air pressure (AP) increased the risk of influenza. Moreover, the interactive effect of low RH with low AT and high AP can aggravate the incidence of influenza.

Research on performance layout and management optimization of Grand Theatre based on green energy saving and emission reduction technology

As far as the Grand Theatre is concerned, it is the core carrier of carrying culture, and it is also an indispensable and important component of cultural undertakings. Based on green energy saving and emission reduction technology, this paper studies the performance layout of grand theatre, establishes BIM (Building Information Model) model with three different Programme, and uses software to simulate energy consumption and analyse thermal comfort of architectural design Programme. Then, according to these working conditions, the indoor design temperature is determined and the building energy consumption is simulated and analysed. It is concluded that when the indoor relative humidity increases from 30% to 50%, the temperature decreases from 24.3 °C to 15.5 °C, and the relative humidity decreases when the indoor temperature increases. According to the different assumptions of the value chain of the Grand Theatre, specific value chain management models of the Grand Theatre are established at macro and micro levels respectively. The establishment of the model enables the value chain theory to be implemented from the conceptual category to the specific operation and management optimization, and deepens the theoretical research on the competitive strategy of the Grand Theatre.

Spatial-temporal variations of terrestrial evapotranspiration across China from 2000 to 2019

Terrestrial evapotranspiration (ET) refers to a key process in the hydrological cycle by which water is transferred from the Earth's surface to lower atmosphere. With spatiotemporal variations, ET plays a crucial role in the global ecosystem and affects vegetation distribution and productivity, climate, and water resources. China features a complex, diverse natural environment, leading to high spatiotemporal heterogeneity in ET and climatic variables. However, past and future ET trends in China remain largely unexplored. Thus, by using MOD16 products and meteorological datasets, this study examined the spatiotemporal variations of ET in China from 2000 to 2019 and analyzed what is behind changes, and explored future ET trends. Climate variation in China from 2000 to 2019 was statistically significant and had a remarkable impact on ET. Average annual ET increased at a rate of 5.3746 mm yr−1 (P < 0.01) during the study period. The main drivers of the trend are increasing precipitation and wind speed. The increase in ET can also be explained to some extent by increasing temperature, decreasing sunshine duration and relative humidity. The zonation results show that the increase in temperature, wind speed, and precipitation and the decrease in relative humidity had large and positive effects on ET growth, and the decrease in sunshine duration had either promoting or inhibiting effects in different agricultural regions. Pixel-based variations in ET exhibited an overall increasing trend and obvious spatial volatility. The Hurst exponent indicates that the future trend of ET in China is characterized by significant anti-persistence, with widely distributed areas expected to experience a decline in ET. These findings improve the understanding of the role of climate variability in hydrological processes, and the ET variability in question will ultimately affect the climate system.

Effect of water‐to‐cement ratio on internal relative humidity and autogenous shrinkage of early‐age concrete internally cured by superabsorbent polymers

AbstractSelf‐desiccation is one common phenomenon of concrete with low water‐to‐cement (w/c) ratios, which may lead to the decrease of internal relative humidity (IRH), and therefore causing autogenous shrinkage (AS). Superabsorbent polymers (SAPs) are used as a kind of internal curing material to mitigate AS of concrete. The IRH and AS are significantly affected by the w/c ratio, and several attempts have been made to investigate the IRH or AS of concrete with different w/c ratios. However, the prediction model of AS considering IRH and w/c ratio of internally cured (IC) concrete is limited. In the present study, the effect of w/c ratio on IRH and AS of IC concrete was investigated, and a two‐stage prediction model of AS based on the results of IRH for IC concrete considering the effect of w/c ratio was proposed. The experiment results and analysis indicated that IRH of IC concrete increased as increase of w/c ratio, and development of IRH experienced two stages: a water‐vapor saturated stage with 100% RH (stage I), and a gradually reducing stage in which IRH decreased gradually (stage II); critical time of IC concrete increased as increase of w/c ratio; expansion peak of IC concrete increased as increase of w/c ratio; AS and AS rate of IC concrete decreased as increase of w/c ratio; IRH, critical time, and expansion peak of IC concrete were higher than that of ordinary concrete; AS and AS rate of IC concrete were lower than that of ordinary concrete.

The deep blue day is decreasing in China.

The deep blue sky is an indicator of a lower concentration of aerosols and a cloudless sky. With increasing human emissions, a trend towards days with fewer deep blue skies might indicate a decline in a good living environment for humans. This study investigates the long-term changes of the deep blue sky in China from 1980 to 2018. Due to a lack of direct measurements, we use atmospheric visibility and low cloud cover to classify blue sky days into three grades: light blue day, medium blue day, and deep blue day. Climatologically, annual deep blue days increase from southeast China to northwest China, with the maximum number in Xinjiang and eastern Inner Mongolia and the minimum number in western Qinghai and southern Hebei. From 1980 to 2018, annual deep blue days show a prominent decreasing trend in most of China, with area-mean annual deep blue days decreasing by −0.48 days per year (d/y) in China, and the variation becomes more obvious after 2013. The maximum decreasing trend is observed in eastern China. The most prominent decreases of deep blue days are seen in winter. Both air pollution and the change in meteorological conditions contribute to the decrease of wintertime deep blue days in China. Specifically, the decrease in surface wind speed hinders the cleaning of air by winds, the increase in surface air temperature, and decrease in relative humidity is favorable for low cloud increase, and the increasing emission of pollution reduces atmospheric visibility.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00704-021-03898-1.

Differential Effects of Abiotic Factors on the Insecticidal Efficacy of Diatomaceous Earth against Three Major Stored Product Beetle Species

This study evaluated the influence of temperature and relative humidity (RH) on the insecticidal effect of diatomaceous earth (DE) at two concentrations, 500 and 1000 ppm, on wheat, for the control of Cryptolestes ferrugineus (Stephens) (Coleoptera: Cucujidae), Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae). These bioassays were carried out in all combinations of four temperature levels (15, 20, 25, and 30 °C), and two relative humidity levels (55 and 75%). Cryptolestes ferrugineus and O. surinamensis were found to be much more susceptible to the DE-treated wheat than T. confusum, but the increase of the DE dose increased the mortality level for all three species. Although the increase of temperature and the decrease of RH increased insect mortality in some of the combinations tested, the reverse was observed in some treatments, suggesting that there are considerable differential effects of these factors in DE efficacy. The increase of insect exposure from 1 to 21 days notably increased insect mortality, suggesting that exposure is a critical factor that may alleviate possible differential effects of certain abiotic conditions. The results of the present work provide data that illustrate the viability of the utilization of DE in stored product protection, as alternatives to chemical control methods.

Climate variability and seasonal patterns of paediatric parainfluenza infections in the tropics: An ecological study in Singapore.

Evidence of the relationship between climate variability, air pollution and human parainfluenza virus (HPIV) infections has been inconsistent. We assessed this in a paediatric population from a highly urbanized tropical city-state. We analysed all reports of HPIV infections in children <5 years old obtained from a major specialist women and children's hospital in Singapore. Assuming a negative binomial distribution and using multivariable fractional polynomial modelling, we examined the relations between climate variability, air quality and the risk of HPIV infections, adjusting for time-varying confounders. We identified 6393 laboratory-confirmed HPIV infections from 2009 to 2019. Every 1°C decline in temperature was associated with a 5.8% increase (RR: 0.943, 95% Confidence Interval [95% CI]: 0.903-0.984) in HPIV infection risk 6 days later. Every 10% decrease in relative humidity was associated with a 15.8% cumulative increase in HPIV risk over the next 6 days (cumulative RR: 0.842, 95% CI: 0.771-0.919). Rainfall was positively associated with HPIV risk 2 days later (RR: 1.021, 95% CI: 1.000-1.043). A within-year seasonal rise of HPIV was driven by HPIV-3 and HPIV-1 and preceded by a seasonal decline in temperature. Gender was an effect modifier of the climate-HPIV relationship. Air quality was not associated with HPIV risk. This study demonstrates a close association between HPIV infection risk and tropical climate variability. The climate dependence and seasonal predictability of HPIV can inform the timing of community campaigns aimed at reducing infection risk and the development of hospital resources and climate adaption plans.

Сurrent condition of pine plantations of Kyiv Polisya under the influence of environmental factors

The article describes the climate change in the study region for the period 1968-2020. It was specified that over the past fifty-nine years there has been an increase in average annual air temperature by 2,5°C, a decrease in relative humidity by 6,0% and average annual rainfall by 5 mm. According to the analysis, it was determined that during the period 2009-2020 significant damage to pine plantations of Kyiv Polissya is caused by the pests like common pine sawfly (Diprion pini L.), pine bark beetle (Aradus cinnamomeus Panz), pine silkworm (Dendrolimus pini L.), pine weevil (Leucaspis pusilla Loew), and pine star weaver (Acantholyda nemoralis Matsumura). Heterobasidion annosum (Fr.) Bref. has also caused a significant damage to pine forests over the past eleven years; the damaged area is of ​​12,8-15,9 thousand hectares.&#x0D; According to the hydrothermal analysis of the study area, it was determined that 2009 and 2015 were characterized as years of medium drought; 2010, 2016, 2017, 2020 were the years of low drought; 2011–2014, 2018, 2019 were the years of sufficient moisture supply. The analysis of the number W influence found that in the years of increased solar activity the number of phytopests increases, while in the years of minimal solar activity it decreases. Based on the statistical indicators, the analysis of CO2 emissions into the environment for the period 2009-2020 and it was found that since 2012 the amount of carbon dioxide emissions has decreased from 10,2 million tons to 3.7 million tons. Correlation analysis of all indicators showed the interaction between the area of ​​damaged trees by insect pests and the Wolf number, CO2 emissions into the environment, average annual precipitation amounts and hydrothermal moisture coefficient of Selyaninov G.T. There is also a correlation between the area of ​​damaged plantations by pine fungus and the average annual air temperature, relative humidity and CO2 emissions.

Influence of environmental factors on spatial and temporal variability of allergenic Artemisia pollen in Beijing, China

Artemisia pollen is an important allergen source of respiratory allergy in Beijing, China. However, there are few pollen stations using Burkard pollen traps in Beijing, and few reports on Artemisia pollen. This research is to analyze annual, daily and diurnal variations in Artemisia pollen concentration in four monitoring stations of Beijing during 2015–2018, and then to investigate their affecting factors. Artemisia pollen season starts in late July or early August, and ends in late September and early October. Daily peak appeared in late August or early September, and diurnal peak emerged during 06:00 - 10:00 or 17:00 - 20:00. Difference in vegetation coverage between urban (less than 1%) and suburban (27.2%) stations within 500 m greatly determined difference in SPI (Seasonal pollen index) between urban and suburban. Temperature and rainfall in the period prior to pollen season, together with the frequency and wind speed of dominant wind direction were responsible for annual variations of SPI. On a daily timescale, temperature was the most important factor influencing pollen concentration, explaining 18.6–43.9% of variance. In the course of the day, increase in temperature and decrease in relative humidity contributed to dehiscence of the anther in the early morning, leading to diurnal peak after sunrise. Wind may dilute or give a rise to the locally released pollen grains depending on the wind speed. High-intensity rainfall (intensity: > 2 mm h-1) had washing-off effects on pollen concentration in the atomosphere, Besides air masses originated from the southerly, northerly and northwesterly directions influenced daily pollen peak by long-range transport. Multiple regression model for each station was constructed to predict daily pollen concentration using previous pollen concentrations and previous meteorological variables in three years, explaining 51.8–75.3% of variance.

Design, construction and implementation of relative humidity and temperature climatic chamber for metrology laboratory

For the calibration of thermohygrometers it is necessary to have a means of generating temperature and relative humidity for this reason in this development we will build a climatic chamber which will generate and control these two magnitudes. For the generation of temperature a thermoresistance was used and the decrease of relative humidity was done through a silica gel trap through which the air inside the chamber is recirculated with the use of a vacuum pump. On the other hand, an ultrasonic humidity generator also known as fogger was used to increase the relative humidity. For the construction of the chamber, acrylic was used as the main material, since it is translucent and facilitates the visualization of the thermohygrometers’ indications. For the control of the process variables such as temperature and relative humidity, an Arduino card was used, which through PWM pulse width modulation, the control was performed achieving a variation of 0.3 °C and 2 %RH, which will be evaluated by an accredited laboratory in the characterization of isothermal media certified by ONAC, since it is in this way that the inhomogeneity, stability and thermal load of the medium, components that affect the uncertainty of the instruments under calibration, are evaluated. It should be remembered that this development was carried out in order to create an air medium with which temperature and relative humidity measuring instruments can be calibrated in the metrology laboratory VALIDACIONES Y METROLOGIA LM S.A.S., since it is in the process of growth and one of its main objectives is to be accredited in the magnitudes of temperature and relative humidity before the accreditation body in Colombia (ONAC), which is the entity that will finally give the technical approval to release the chamber and put it into operation.

Wpływ znaku faz NAO w okresie zimowym na bilans wodny i możliwości wystąpienia suszy w ciepłej porze roku na obszarze Polski

The study shows that the change in the NAO phase has an impact on the formation of the area averages of the most important climatic elements during winter, with the exception of winter precipitation totals. An increase in air temperature, wind speed and sunshine duration, and a decrease in cloudiness and relative humidity during the occurrence of positive NAO phases lead to an increase in field evaporation. Evaporation in winter, calculated by Ivanov’s method, shows strong and highly significant positive correlation with the value of the winter NAO index. Thus, the water balance changes, negatively affecting the size of the soil retention. Changes in the NAO index in the winter period have such a strong influence on the water balance in Poland that their influence is detected in the course of the value of the total annual outflow of Polish rivers. Additionally, after the occurrence of a positive NAO phase in winter, in May and August the sums of precipitation (in August – highly significantly), cloudiness and relative humidity decrease, and sunshine duration increases. This is an inertial effect of the winter NAO of unidentified genesis. Both the increase in evaporation in winter and the delayed effect of winter NAO contribute to an increase in the probability of a drought in the summer following winter, during which the NAO sign was positive.

Observed increases in extreme fire weather driven by atmospheric humidity and temperature

Recent increases in regional wildfire activity have been linked to climate change. Here, we analyse trends in observed global extreme fire weather and their meteorological drivers from 1979 to 2020 using the ERA5 reanalysis. Trends in annual extreme (95th percentile) values of the fire weather index (FWI95), initial spread index (ISI95) and vapour pressure deficit (VPD95) varied regionally, with global increases in mean values of 14, 12 and 12%, respectively. Significant increases occurred over a quarter to almost half of the global burnable land mass. Decreasing relative humidity was a driver of over three-quarters of significant increases in FWI95 and ISI95, while increasing temperature was a driver for 40% of significant trends. Trends in VPD95 were predominantly associated with increasing temperature. These trends are likely to continue, as climate change projections suggest global decreases in relative humidity and increases in temperature that may increase future fire risk where fuels remain abundant.

Estimate of The Dynamical Change of Air TemperAture, Relative Humidity and Dew Point TemperaTure for Some Selected Station in Iraq

Relative humidity can be inferred from the dew point values. When the air temperature and dew point temperatures are very close, the air has high relative humidity. The converse is true when there is a large difference between the air temperature and the dew point temperature, indicating the presence of low humidity air. To understand the expected changes in the climatic elements in the atmosphere, changes in temperature behavior, dew point, and relative humidity have been studied This study used data obtained from the European Center (ECMWF), which includes monthly and annual mean temperatures, dew, and relative humidity during the period (1988-2018) for selected stations in Iraq. The highest values of temperature and dew were recorded in July and August, and they were accompanied by a decrease in relative humidity. The highest value of relative humidity was recorded in December and January, accompanied by a decrease in temperature and dew, as we note through the results that there is an inverse relationship between relative humidity, temperature, and dew point Relative humidity changes when the temperature rises or falls, and the relative humidity may be higher in the morning when the temperature drops. The lowest amount of relative humidity during the day is when the temperature rises, the highest temperature value was recorded on 21July 2017 (12:00 PM) for Basra Station, while the highest relative value is humidity in Basra Governorate. Mosul station on January 21, 2014 (12:00 AM), and the reason is due to meteorological factors and the nature of the geographical area.

Asymmetric response of short- and long-duration dry spells to warming during the warm-rain season over Eastern monsoon China

Changes in dry spell duration have been analyzed over China and worldwide. However, the asymmetric response (i.e. skewed distribution) of short- and long-duration dry spells to warming temperature and possible mechanisms remain unknown. Here, we investigate this response based on daily weather observations during the warm-rain season (May-September) over 1961–2019 from 1540 quality-controlled stations across Eastern Monsoon China (EMC). Our results show a 1℃ warming in surface air temperature (SAT) and a considerable elongation of dry spells. Specifically, the regional average, maximum, and total dry spell duration over EMC increased by +7.06%, +6.17%, and +5.16%, respectively over 1961–2019. The areas in EMC with long dry spells and high SAT are also the areas that have experienced faster increases in the duration of dry spells per degree of warming. We find increases in the frequency of long-duration dry spells, but significant decreases in the frequency of short-duration dry spells. The increasing frequency of long-duration dry-spells can be explained by the slight increase in land evaporation (+1.6%/℃) over EMC and the decrease in integrated moisture vapor transport (-3.8%/℃) with warming, such that atmospheric moisture sources cannot meet the warming-induced demand, resulting in significant decreases in relative humidity (−2.4%/℃) and precipitation (−7.0%/℃). In contrast, the decreasing frequency of short-duration dry spells during hotter warm-rain seasons occurs when the saturation vapor pressure deficit is enhanced, leading to prolonged periods where the atmosphere is replenished to necessary saturation levels for local precipitation. Relative to cold warm-rain seasons, hot warm-rain seasons with higher SAT witness cold-dry air advection in the upper level, lower convective available potential energy, and stronger vapor divergence over EMC, which tends to suppress precipitation occurrence. With future warming, the increasing frequency and duration of dry spells in the warm-rain season is likely to be conducive to the occurrence of severe droughts and heatwaves in EMC, with negative impacts on socio-economic development in China.