Cold Dry Air Research Articles

A Comparison of Extreme and Ordinary Freezing Rain Events of Long Duration and High Integrated Vapor Transport in Eastern North America

Abstract Freezing rain events of long duration (LD, at least 12-h) in two study domains of eastern North America gleaned from the database of McCray et al. (2019) are examined using ERA5 reanalysis-based integrated vapor transport (IVT) to investigate how parent cyclones with high IVT (HIVT; surrogate for atmospheric rivers) contribute to severe freezing rain events. Although not necessary for an LD freezing rain event to occur, HIVT-influenced parent cyclones are associated with most (70%) events occurring in the southeastern Canada/ northeastern U.S. study domain (CAUS) and with the majority (78%) of very long (at least 24-h) LD events in the region over a 38-year period (1979-2016). Comparing extreme and ordinary LD events involving HIVT-influenced parent cyclones over the CAUS and southeastern U.S. study domains shows the importance in extreme events of slow movement and phasing between the continental parent cyclone located over eastern North America and a corresponding mid-latitude anticyclone to the northeast of the CAUS domain that provides cold dry air needed in the near-surface cold layer to offset opposing diabatic effects. A corresponding sub-tropical anticyclone assists the parent cyclone in supplying warm and humid air at mid-levels of freezing rain events to the northern reaches of the study domain, extending spatial and temporal scales of extreme events. Most ordinary LD event parent cyclones are progressive and impact the study domain only briefly. An abrupt end of ordinary LD events having a slow-moving parent cyclone occurs either when its center moves over the study domain or a second, newly dominant cyclone emerges.

Future Climate Change in the Northern Bering Sea

ABSTRACTThe Bering Sea is undergoing major changes from increasing winter temperatures to the north, extreme minimum sea‐ice years in 2018 and 2019, through to an ecosystem reorganisation and negative impacts on communities' economic and subsistence food resources. These events have emerged under a global warming background, with positive feedback processes through a weakened atmospheric Alaskan Arctic Front (AAF) that promotes a self‐reinforcing process of sea‐ice loss, warmer air and sea temperatures, a wavy jet stream, and southerly winds. Interannual variability is still important: during 2021–2024 the Aleutian Low‐pressure system was regionally dominant in supporting a strong AAF, and sea‐ice conditions were observed close to the climatological mean. Before 2017, the AAF, consisting of cold dry air mass to the north and moist relatively warm air mass to the south, was a barrier to northward movement of storms, keeping the northern Bering/Chukchi seas with a cold Arctic climate. That historical situation is ending. Of critical importance is the probable reoccurrence of low Bering Sea sea‐ice years over the next decades and related ecosystem impacts. We propose that radically low sea ice will have a frequency of one to three 2018‐like low sea‐ice events per decade in the coming two decades, based on a historical meteorological analysis and ensemble climate model projections. Arctic temperatures to the north are increasing, weakening their contribution to the AAF. A weakened AAF and low sea‐ice years needs the winter Aleutian low pressure system to be far to the west of its average position, with southerly rather than northeasterly winds, warm years and low sea‐ice extent. From 1948 to 2024 meteorological records, this western location occurred with a range of zero to three times per decade. Communities need to plan for a response to intermittent occurrence of 2018‐like extreme sea‐ice loss and their ecosystem impacts over the coming decades.

Rare presence and function of neuroendocrine cells in the nasal mucosa.

There is growing evidence that neurogenic inflammation contributes to the pathophysiology of upper airway diseases, with nasal hyperreactivity (NHR) being a key symptom. The rare neuroendocrine cells (NECs) in the epithelium have been linked to the pathophysiology of bronchial and intestinal hyperreactivity, however their presence in the nasal mucosa and their potential role in NHR remains unclear. Therefore, we studied the presence of NECs in the nasal epithelium of controls, allergic rhinitis patients and chronic rhinosinusitis with nasal polyps patients, and their link to NHR. The expression of typical NECs markers, CHGA, ASCL1 and CGRP, were evaluated on gene and protein level in human samples using real-time quantitative PCR (RT-qPCR), western blot, immunohistochemistry fluorescence staining, RNA scope assay, flow cytometry and single cell RNA-sequencing. Furthermore, the change in peak nasal inspiratory flow after cold dry air provocation and visual analogue scale scores were used to evaluate NHR or disease severity, respectively. Limited gene expression of the NECs markers CHGA and ASCL1 was measured in patients with upper airway diseases and controls. Gene expression of these markers did not correlate with NHR severity nor disease severity. In vitro, CHGA and ASCL1 expression was also evaluated in primary nasal epithelial cell cultures from patients with upper airway disease and controls using RT-qPCR and western blot. Both on gene and protein level only limited CHGA and ASCL1 expression was found. Additionally, NECs were studied in nasal biopsies of patients with upper airway diseases and controls using immunohistochemistry fluorescence staining, RNA scope and flow cytometry. Unlike in ileum samples, CHGA could not be detected in nasal biopsies of patients with upper airway diseases and control subjects. Lastly, single cell RNA-sequencing of upper airway tissue could not identify a NEC cluster. In summary, in contrast to the bronchi and gut, there is only limited evidence for the presence of NECs in the nasal mucosa, and without correlation with NHR, thereby questioning the relevance of NECs in upper airway pathology.

Design and performance test of a fluidized bed dryer using dry cold air flow for drying marungga leaves

The Marungga tree is a plant that offers numerous benefits. Its leaves can be processed into flour for further processing for various needs. Marungga leaves need to be dried before they can be made into flour. Marungga leaves are sensitive to heat, so high temperature drying should be avoided. Drying in the sun, or at room temperature takes a long time and is unhygienic. To address these issues, a fluidized bed dryer that utilises dry, cold air flow through dehumidification of the air is required. This research aims to design and test the performance of a fluidized bed dryer that uses dry cold air flow. The method used in the research starts from literature study, design, component manufacturing, assembly and performance testing of the dryer. The design results resulted in specifications of the dryer components as follows: dimensions of the drying chamber 500 mm in diameter and 800 mm in height, evaporator, condenser, compressor, blower each 1 HP. The results of the dryer performance test are as follows: dryer air temperature 34.2 °C, relative humidity 54.3%, and dryer air mass rate 0.25 kg/s, with a drying rate of 0.57 kgH2O/s. The evaporator of the cooling system can decrease the absolute humidity of the drying air by 1.6 kgH2O/kg dry air.

Oceanic maintenance of atmospheric blocking in wintertime in the North Atlantic

The connection between atmospheric blocking over the North Atlantic and the diabatic influence of the Gulf Stream is investigated using potential vorticity and moist potential vorticity diagnostics in the ERA5 reanalysis data set during wintertime (1979 - 2020). In line with previous research, the reliance atmospheric blocking has on turbulent heat fluxes over the Gulf Stream and its extension, for induction and maintenance, is shown to be significant. The air-sea heat flux generates negative potential vorticity air masses in the atmospheric boundary layer. These air masses subsequently contribute to the block’s negative potential vorticity anomaly at upper levels through ascending motion in the warm conveyor belt. It is shown that the block’s size and frequency partially depends on oceanic preconditioning via anomalous oceanic heat transport and heat content, prior to the blocking event, both of which allow for stronger turbulent heat fluxes. It is further hypothesized that the block feeds back positively on itself through the advection of cold dry air over the Gulf Stream, sustaining this air-sea interaction. This in turn decreases ocean heat content, eventually halting this air-sea interaction and severing the atmospheric block from its maintenance pathway.

Nasal hyperreactivity in allergic rhinitis and chronic rhinosinusitis with polyps: a role for neuronal pathways.

Nasal hyperreactivity (NHR) is prevalent in all chronic upper airway inflammatory phenotypes, including allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP). Although NHR in patients with non-allergic rhinitis is mediated by neuronal pathways, AR and CRSwNP are mainly characterized by type 2 inflammation. Eighteen healthy controls and 45 patients with symptomatic AR/CRSwNP underwent a cold, dry air (CDA) provocation test for objective diagnosis of NHR. Before and after, questionnaires were filled out and nasal secretions and biopsies were collected. Markers for neurogenic inflammation (substance P, calcitonin gene-related peptide, neurokinin A), epithelial activation (IL-33), and histamine were measured in secretions by ELISA; and expression of neuronal markers PGP9.5, TRPV1, and TRPM8 was studied in biopsies by RT-q-PCR. Effects of histamine on TRPV1/A1 were studied with Ca2+-imaging using murine trigeminal neurons. CDA-provocation reduced peak nasal inspiratory flow (PNIF) of patients with subjective NHR but not of non-NHR controls/patients CDA-provocation reduced peak nasal inspiratory flow (PNIF) of patients with subjective NHR but not of non-NHR controls/patients. Subjective (subjectively reported effect of CDA) and objective (decrease in PNIF) effects of CDA were significantly correlated. Levels of neuropeptides and histamine in nasal secretions and mRNA expression of PGP9.5, TRPV1, and TRPM8 correlated with CDA-induced PNIF-reduction. CDA-provocation induced an increase in IL-33-levels. Both TRPV1 and TRPA1 expressed on afferent neurons were sensitized by exposure to histamine. NHR is not an on/off phenomenon but spans a continuous spectrum of reactivity. A neurogenic inflammatory background and increased histamine-levels are risk factors for NHR in AR/CRSwNP.

Why was Pakistan extreme precipitation stronger in 2022 than in 2010?

In Pakistan, five continuous extreme precipitation events in the summer (July‒August) of 2022 caused disastrous floods, depriving thousands of people's lives and ruining millions of hometowns. This tremendous disaster in Pakistan also happened in 2010 but with three concentrated extreme precipitation events in the middle of summer. The amount of Pakistan heavy daily precipitation in 2022 surpasses that in 2010 record, making it the strongest precipitation event ever recorded. To comprehensively understand the causes of extreme precipitation in Pakistan, this study investigated the anomalies in atmospheric circulation and moisture contribution of 2010/2022 extreme precipitation and compared their differences. The results show that an atmospheric blocking over northern Europe in both 2022 and 2010 enhanced convection in Pakistan by transporting cold‒dry air from the high-latitude region and benefiting warm‒wet monsoonal air marching to Pakistan. By employing a moisture track model, the main moisture sources for summer precipitation in Pakistan were identified. It is found that moisture contributions except from Eurasia were enhanced, causing extreme precipitation. In particular, enhanced moisture contribution from the southern Indian Ocean and the northern Indian continent in 2022 are more prominent than that in 2010. The increased moisture contribution in 2010 was due to increased evaporation induced by warming sea surface in the Indian Ocean, while much richer moisture transport in 2022 was attributed to the enhanced cross‒equatorial flow induced by the anomalous subtropical high in the Southern Hemisphere. Therefore, attention should be paid to the role of subtropical high in the Southern Hemisphere in addition to those in Northern Hemisphere in understanding disastrous extreme precipitation events in Pakistan.

Energy and exergy analyses of a hybrid adsorption refrigeration system for simultaneous production of cold water and dry air

Current adsorption refrigeration systems are limited by dehumidification methods and produce either cold water or cold dry air. The single cooling product greatly hinders their application into situations where multiple cooling outputs are needed. In order to address this issue, this paper introduces a hybrid adsorption refrigeration system using efficient desiccant coated heat exchangers to provide both cold water and dry air via the deep utilization of input heat sources. In this study, the performance of the hybrid system is experimentally investigated from a combined perspective of energy and exergy. Results show that the hybrid system can simultaneously output cold water and dry air with a heat source of 50–80 °C. A low-temperature cooling water is beneficial to system performance, while an optimum input hot water temperature exists. At a coolant-side temperature of 25 °C, the COP reaches its maximum of 0.238 under a heat source temperature of 60 °C, and the highest exergetic efficiency is quantified as 13.9% when powered by 50 °C hot water. Increasing inlet air temperature or relative humidity facilitates the COP improvement but has a negligible effect on the exergetic efficiency. In comparison with a traditional adsorption air conditioning system, the hybrid system has a wider range of input hot water temperatures and is more advantageous in terms of cooling exergy and exergetic efficiency. This hybrid system firstly enables adsorption refrigeration to export dual cooling products of cold water and dry air, which is expected to extend adsorption refrigeration into fully automatic industrial fields.

Impacts of Cyclones on Arctic Clouds during Autumn in the Early 21st Century

Our study shows that, during 2001–2017, when the sea ice was melting rapidly, cyclone days accounted for more than 50% of the total autumn days at the sounding stations in the Arctic marginal seas north of the Eurasian continent and almost 50% of the total autumn days at the sounding station on the northern coast of Canada. It is necessary to investigate the influence of Arctic cyclones on the cloud fraction in autumn when the sea ice refreezes from its summer minimum and the infrared cloud radiative effect becomes increasingly important. Cyclones at the selected stations are characterized by a narrow maximum rising zone with vertically consistent high relative humidity (RH) and a broad region outside the high RH zone with low RH air from the middle troposphere covering the low troposphere’s high relative humidity air. Consequently, on approximately 40% of the cyclone days, the cloud formation condition was improved from the near surface to the upper troposphere due to the cooling of strong rising warm humid air. Therefore, cyclones lead to middle cloud increases and sometimes high cloud increases, since the climatological Arctic autumn clouds are mainly low clouds. On approximately 60% of the cyclone days, only low cloud formed, but the low cloud formation condition was suppressed due to the mixing ratio decrease induced by cold dry air sinking. As a result, cyclones generally lead to a decrease in low clouds. However, the correlation between the cyclones and low clouds is complex and varies with surface ice conditions.

Thermodynamic and dynamic effects of anomalous dragon boat water over South China in 2022

In 2022, persistent extreme precipitation events occurred during the Dragon Boat Water (DBW) period (May to June) over South China, with rainfall-breaking historical extremes at many stations. In this study, the relative importance of the thermodynamic and dynamic effects on this anomalous event was explored through budget equations of moisture and moist static energy (MSE). The moisture budget analysis suggests that the thermodynamic effect contributes to the precipitation anomaly by less than 10% through the advection of abnormal moisture by mean horizontal and vertical motion. However, the dynamic effect, associated with the mean moisture advection by anomalous vertical motion, makes the largest contribution. This seems to imply that the increase in water vapor due to global warming does not play a critical role in this extreme event. Nevertheless, further analysis of the MSE budget equation reveals that the anomalous vertical motion is governed by both the dynamical effect of atmospheric circulation changes and the thermodynamic effect of atmospheric thermal state changes. The thermodynamic effect, which accounts for 47.21% of the total effect (sum of the thermodynamic and dynamic effects), is caused by anomalous moist enthalpy (mainly dry enthalpy) advection due to the mean horizontal motion. In contrast, the dynamical effect is related to the warm and humid air advection caused by the anomalous southwest wind caused by the anomalous anticyclone over the northwest Pacific. Simultaneously, the anomalous northeast wind brings dry cold air, resulting in the convergence of cold and warm air over the Pearl River basin and persistent heavy rainfall events. The results of this study provide valuable insights into the direct and indirect physical mechanisms leading to anomalous DBW period over South China in 2022.

USV-Observed Turbulent Heat Flux Induced by Late Spring Cold Dry Air Incursion over Sub-Mesoscale Warm Regions off Sanriku, Japan.

We performed oceanic and atmospheric observations in the region off the Sanriku coast, Japan, from May 11 to 5 July 2022, using a wave-propelled unmanned surface vehicle, a Wave Glider (WG). Despite the severe weather conditions of atmospheric low-pressure system crossings, we successfully measured wind, air temperature, humidity, and sea surface temperature over the course of 55 days to calculate the turbulent heat flux. The WG observed that the atmosphere became more humid due to the southerly wind along the northwestern rim of the North Pacific subtropical high. The warm Kuroshio water expanded to the southeast of Hokkaido as a result of the northward shedding of an anticyclonic mesoscale (~100 km) eddy, called a warm-core ring, from the Kuroshio Extension. The WG traversed smaller (sub-mesoscale) water regions that were warmer and saltier than the surrounding Kuroshio water. The observations indicate that cold, dry air masses advected by northerly winds following the passage of atmospheric low-pressure systems generate a substantial upward turbulent heat flux over sub-mesoscale warm water regions, contrasting to no heat flux in the surrounding Kuroshio water region.

Nasal Reactivity After Radiofrequency Ablation of Peripheral Branches of Posterior Nasal Nerve.

Transection or ablation of the posterior nasal nerve (TRPN) has been described as an adjunctive tool to reduce the symptoms of intractable allergic rhinitis (AR). The procedure, however, requires surgical skill and carries the risk of bleeding from the sphenopalatine artery. The aim of the present study is to describe radiofrequency ablation of the peripheral branches of the posterior nasal nerves within the inferior turbinates (RAPN) as an effective easier alternative to TRPN. The procedure was performed on 24 patients with intractable AR. Nasal reactivity was tested by cold dry air (CDA) provocation before and 12 months after the radiofrequency procedure. Visual analog scale and acoustic rhinometry were used to measure the changes in nasal reactivity subjectively and objectively. Worsening of nasal symptoms following CDA provocation had significantly decreased after the RAPN procedure. Likewise, postoperative decrease in nasal volumes and minimal cross-sectional areas after CDA provocation were significantly less than the corresponding preoperative values. RAPN effectively reduces nasal reactivity in patients with AR. The procedure is simple, minimally invasive, and can be performed under local or general anesthesia.

Application of a Cold Dry Air Provocation Test in Pediatric Patients with Asthma.

Asthma is a chronic inflammatory airway disease characterized by reversible airway obstruction and airway hyperreactivity. We proposed a cold dry air (CDA) provocation test and investigated its application in pediatric patients with asthma. We enrolled 72 children and adolescents older than 5 years who presented to our hospital with chronic cough, shortness of breath, and wheezing. We analyzed the results of allergy, pulmonary function, methacholine provocation, and CDA provocation tests. The FEV1 change 5 min after the provocation was recorded as CDA5 dFEV1; that after 15 min was recorded as CDA15 dFEV1. PT10 was the provocation time causing a 10% decrease in FEV1; a decrease of >10% in dFEV1 was considered a positive CDA test. Among the 72 subjects, 51 were diagnosed with asthma. A positive CDA test in patients with asthma correlated with non-eosinophilic asthma. In patients with asthma, sputum eosinophils and eosinophil cationic protein (ECP) levels of the patients with a positive CDA test were significantly lower than those of patients with a negative test. CDA5 dFEV1 correlated with PC20 and total immunoglobulin E. CDA15 dFEV1 correlated with PC20, sputum eosinophils, and ECP. PT10 became shorter as the peripheral blood eosinophil, FVC, FEV1, FEV1/FVC, and FEF25-75 decreased. The CDA provocation test showed airway hyperreactivity to non-specific stimuli, a high correlation with non-eosinophilic asthma, and the possibility of assessing asthma severity via PT10.

Comparative Analysis on Two Severe Convective Processes in Hunan Province in 2020

In this study, two severe convective weather processes in late March 2020 are compared and analyzed based on the surface observation data, Doppler weather radar data, satellite black body temperature data and the reanalysis data from the National Centers for Environmental Prediction. The results show that the two severe convective weather processes both can be divided into two stages, warm advection forcing stage and baroclinic frontogenesis stage. For the second process the warm advection forcing is not significant. In terms of dynamic conditions, in both processes there is low-level convergence, high-level divergence, middle-low-level southwesterly jet, and the intrusion of cold air. The upward motion in the second process is more intense than that in the first process. In both processes, the upward motion in the warm advection forcing stage is weaker than in the baroclinic frontogenesis stage. In the aspect of water vapor conditions, the divergence of water vapor flux at 850 hPa in the second process is larger than that in the first process. The water vapor convergence center rises to the level above 800 hPa and lasts for a long time. Through the comparative analysis in different stages, it is found that the water vapor convergence in the two processes in the baroclinic frontogenesis stage is stronger than that in the warm advection forcing stage. For the thermal conditions, the cold-dry air at high levels is superimposed over the warm-wet air at low levels, presenting a thermal unstable stratification. In the first process, the intensity and vertical extension of the low-level warm advection is larger than that in the second process. In both processes, the unstable energy is accumulated obviously in the warm advection forcing stage, and is released to a certain extent before the baroclinic frontogenesis stage. In the first process, there are 3 supercells within 100 km from ChangDe radar. In both processes, there are hails from 1900 BJT (Beijing Time) to 2000 BJT in Guanzhuang Town. The radar echoes both present the typical characteristics of hail. In the first process, the maximum reflectivity factor is larger, the intensity and vertical extension of mesocyclone are larger, the increase of vertical integrated liquid is more significant, and the high-level divergence is more intensive. Thus, the diameter of hail in the first process is larger.

Impact of synoptic climate system interaction on surface ozone in China during 1950–2014

The effects of meteorological conditions controlled by specific synoptic patterns on regional surface ozone episodes have been widely discussed. However, the impacts of synoptic climate systems and their interaction on long-term variation of ozone are less known. In this study, we use the daily meteorological data and hourly surface ozone concentrations in the summer of 1950–2014 from CMIP6 to investigate the relationship between ozone variations and synoptic climate types (SCTs). Eight SCTs are identified by an objective circulation classification method of an R package called synoptReg. Our results show that the mainland of China is controlled by the low-pressure system for SCT1–5, while dominated by Siberian high for SCT6–8. During SCT1–5 days, the interactions of Asian continental low, Western Pacific Subtropical High (WPSH), warm ridge at 700 hPa, high-level shallow Asian trough, westerly belt, and topography lead to high surface temperature, low relative humidity, and poor diffusion over Northern China with frequent ozone exceedance days. However, the low-level ozone concentrations over Northern China are shown under SCT6–8, affected by the weakened Asian continental low, enhanced Siberian high, stronger WPSH, and denser westerly belt. While over Southern China, ozone concentrations are higher for SCT6–8 than SCT1–5, due to the significantly reduced cloud and precipitation affected by the delivery of cold dry air mass from high latitudes to the South. The interdecadal variabilities of ozone during all SCTs may be controlled by the large-scale climate system of the East Asian monsoon.

Cold Air Outbreaks Promote New Particle Formation Off the U.S. East Coast

AbstractNew particle formation (NPF) is the dominant contributor to total particle number concentration and plays an important role in the cloud condensation nuclei budget. Airborne data from Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) are used to address seasonal NPF statistics and factors related to NPF in and around clouds. Higher ratios of particle concentrations greater than 3 versus 10 nm (N3/N10) were mainly observed above boundary layer cloud tops during winter as compared to summer. Cold dry air and low aerosol surface area concentration facilitate NPF over the ACTIVATE region; these conditions are especially prevalent during flights coinciding with cold air outbreaks.

Comparative Evaluation of Lung Functions between Ac and Non Ac users among Student Population

Background: Usage of air conditioners (AC) has been highly increased in this modern era. In addition to the cooling of the environment, it has a major impact on human health. Rapid influx of cold dry air increases the risk of bronchoconstriction in asthma patients due to the dehydration of the air pathway. So, the present study planned to comparatively evaluate the lung functional status in air conditioner and non air conditioner users.
 Materials and Methods: The pulmonary functional capacity was assessed using FVC, FEV1 and FEV1/FVC ratio, Peak expiratory flow rate (PEFR) and FEF 25-75% in a Helios 702 spirometer.
 Results: The lung functional capacities among the AC users showed a statistically significant decline in PEFR and FEF25-75% indicating the risk of airway obstruction.
 Conclusion: The study concluded an innovative finding that AC users are developing ventilatory dysfunction and are at more risk of respiratory dysfunction. The coldness of the aerosol of the AC unit or other factors responsible may be allergens, infections and humidity level. Thus technical and hygienic features of air intake must be ensured to maintain a good indoor air quality.

Effect of Air Conditioner on Pulmonary Function Tests of Healthy Males in India

Advances in Medical, Dental and Health Sciences,2021,4,3,26-30.DOI:10.5530/amdhs.2021.3.6Published:December 2021Type:Research ArticleAuthors:Mehraj Trumboo, and Kulbir Singh Author(s) affiliations:Mehraj Trumboo1, Kulbir Singh2,* 1Senior Medical Officer, District Hospital (DH), Poonch, Jammu and Kashmir, INDIA. 2Department of Surgery, Government Medical College, Anantnag, Jammu and Kashmir, INDIA.Abstract:Aim of our present study was to evaluate the effect of AC on pulmonary functions in healthy persons who routinely use AC, like bank employees and compare them with normal healthy volunteers who do not use AC. A comparative study covering a total of 100 subjects divided into two groups (Group-A and Group-B). Group-A (Cases)consisted of 50 healthy male subjects exposed to air conditioner in their work place namely Bank offices for a period of 7to 8 hr for 5 days a week over a period of two consecutive years. Group-B (Controls)consisted of male subjects working in the Higher Education Department who were not exposed to air conditioner during their work for last two years.In the present study, there is a significant difference between Group A and Group B with respect to FVC as p= 0.0001. Also, there is significant difference between Group A and Group B with respect to FEV1 as p= 0.001. A significant difference was seen between Group A and Group B with respect to FEF25-75% as p=0.0001.Exposure to air conditioner in bank employs leads to significant decrease in pulmonary functions as compared to non-air conditioner users. The inhalation of dry cold air causes both small and large airways obstructive lung disease, as is reflected by the decreased parameters like FVC, FEV1, FEV1/FVC ratio, FEF25-75%, PEFR and MVV. Keywords:FEF, FEV, FVC, MVV, PEFR., Pulmonary function testsView:PDF (428.26 KB)

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.

Transient Response of Ventilated Room Enclosure Subjected to Solar Radiation Load

The effect of incident solar radiation ray’s penetration through glassed windows of duct - ventilated room enclosure air is investigated assuming constant solar intensity. The room is supplied with cold dry air through rectangular duct and the air is distributed through two grid ceiling fans located at the duct exit. The effect of fixed solar intensity penetration with variable fans rotational speed at specified time intervals is investigated upon the room temperature distribution and is simulated using the ANSYS CFX package. The results showed the variation in room temperature distribution at a specified time period (1, 2, 3 minutes) with increased fan speed becomes more efficient, also the transient room temperature distribution response to the solar radiation is significantly present in the simulation noticing fans effect on accelerating heat transfer rate through the domain.