Moisture Sources Research Articles

Climate variability in a 3.8 Ma old sedimentary record from the hyperarid Atacama Desert

The hyperarid Atacama Desert is one of the driest and oldest deserts on Earth, rendering it a valuable climate archive. However, unraveling its past climate is particularly challenging and the few studied paleoclimate records of the region reveal strong temporal and spatial variabilities. To enhance our understanding of these dynamics we investigated a sedimentary record in the Yungay valley located in the southern hyperarid Atacama Desert. We employed paleomagnetic and radiocarbon dating, and for the first time for Atacama Desert sediments, a meteoric 10Be/9Be based method for determining the depositional age. The respective 4.20 m deep profile comprises a lower alluvial fan deposit with a maximum age of 3.8 ± 0.8 Ma, and an upper 1.84 m thick clay pan deposit that has accumulated over the last 19 ka. Different proxies including grain size, salt concentration, and elemental composition indicate an aridity increase around 2.3 Ma ago and repeated dry and wet phases during the late Pleistocene and the Holocene. The latter climatic shifts can be assigned to variabilities of the South American Summer Monsoon and El Niño Southern Oscillation with moisture sources from the Atlantic and the Pacific Ocean, respectively. This study provides deeper insights into the heterogeneous climate of the hyperarid Atacama Desert and underlines the importance of interdisciplinary investigations to decipher climate systems and their effect on potential habitable regions in such an extreme environment.

Impact of Arctic Stratospheric Polar Vortex on Mediterranean Precipitation

Abstract The Mediterranean precipitation has significant implications for the local ecology and human livelihoods. This study explores the impact of the Arctic stratospheric polar vortex on the Mediterranean precipitation during the wet season (winter) using reanalysis data and large-scale ensemble experiments that are forced by anomalous stratospheric polar vortex states. Our findings reveal that total and extreme precipitation over the Mediterranean region are increased under weak polar vortex (WPV) conditions and decreased under strong polar vortex (SPV) conditions. Moisture budget suggests that the changes in vertical motion over the Mediterranean play the dominant role in precipitation changes. It is further found that the tropospheric quasi-stationary wave train propagating from Greenland to the European continent is enhanced under WPV conditions, accompanied by warming advection over the eastern Mediterranean and vorticity advection in the upper troposphere over the whole region of the Mediterranean. Consequently, the vertical motion and precipitation there are enhanced. The southward shift of the Atlantic jet stream under WPV conditions leads to enhanced moisture transport toward the Mediterranean, providing a favorable moisture source for precipitation. In addition, the background baroclinicity in the lower troposphere around the northern Mediterranean is enhanced under WPV conditions, intensifying frontogenesis and cyclonic activities, which are commonly accompanied by intensified precipitation. These results are consistent with earlier literature and suggest that the changes in the stratospheric polar vortex may be used as a potential predicting factor for Mediterranean precipitation.

Grand dipole response of Asian summer monsoon to orbital forcing

The coherent continental-wide speleothem water isotope records are accompanied by regionally inconsistent moisture patterns within the Asian summer monsoon (ASM) region, leaving a disputed explanation of monsoonal hydroclimate variability at the orbital timescale. Here, the transient simulation forced by orbital parameters during the past 300,000 years in an isotope-enabled fully coupled model shows that the complex ASM response can be understood as a grand dipole pattern of oxygen isotope and rainfall between South Asia and Japan, with South China lying in a hybrid transition region. While the dipole monsoon rainfall change between South Asia and Japan is related to the large-scale circulation adjustment in response to Northern Hemisphere summer insolation, the dipole oxygen isotope pattern is associated with the changing contribution of moisture sources. Our results provide new clues to reconcile ASM hydroclimate patterns at orbital timescale as revealed by the water isotope records and other hydrological proxies.

Orbital modulation of subtropical versus subantarctic moisture sources in the southeast Pacific mid-latitudes

Reconstructing rainfall variability and moisture sources is a critical aspect to understand past and future hydroclimate dynamics. Here, we use changes in the deuterium content of land-plant leaf waxes from two marine sediment cores located off Chile to reconstruct changes in rainfall amount and variation in moisture sources over the last ~50 ka. The records indicate increased moisture in central Chile during precession maxima, but an obliquity modulation is evident in southern Chile. While the southern westerly winds are the dominant factor of precipitation in southern Chile by bringing moisture and perturbations from the extratropics, the subtropics represent an additional moisture source during precession maxima due to a stronger subtropical jet increasing moisture transport from the tropics to the mid-latitudes. These findings imply that a combination of orbital modulation of moisture sources and rainfall amount explains the last glacial moisture maximum and early Holocene moisture minimum in south-central Chile.

The Role of Atmospheric Rivers Moisture Origin in the Seasonality of Extreme Precipitation in the Eastern United States

Abstract Regional patterns of the seasonal weather and atmospheric moisture origins can impact the seasonal activities of extreme precipitation in the eastern United States (eUS). At many locations, tracks of atmospheric moisture can have different influence on timing of extreme precipitation based on the moisture origin source. In this study we evaluate the contribution of Atmospheric Rivers (ARs), and their moisture origin sources to the distribution and seasonal effectivity of annual maximum precipitation (AMP) across the eUS during 1950–2021. Our results suggest that AR is a dominant mechanism of AMP in the eUS as they contribute to 75% (31,438 out of 41,976) of total AMP events recorded between 1950–2021. The seasonal analysis based on circular density approach shows that spring, summer and fall seasons display strong signals of seasonality of AMP-AR events. The spatial patterns of AMP associated with the four major moisture sources (the Pacific Ocean, the Atlantic Ocean, the combined source of Caribbean Sea and Gulf of Mexico, and the local source of moisture) reinforce the key role ARs play in transporting water vapor to eUS from both oceanic and inland originated moisture. The results additionally highlight the importance of moisture sub-sources (major sources sub-regions) in modulating the seasonality of extreme precipitation in the eUS.

Seasonal Variations and Controls on Triple Oxygen and Hydrogen Isotopes in Precipitation—A Case Study From Monitoring in Southwest China

AbstractPrecipitation δ18O has offered valuable insights into the evolution of the Asian monsoon. Recent researches focusing on precipitation Δ′17O has enhanced our understanding by offering new perspectives beyond those of δ18O, revealing insights into vapor sources and continental recycling. Nevertheless, there remains a lack of interannual triple oxygen isotope data, particularly in the Asian monsoon region. In this study, we analyzed the triple oxygen isotopes and hydrogen isotopes in monthly precipitation samples collected from Chongqing in Southwest China between 2019 and 2022 A.D. Seasonal variations in δD, δ18O, δ17O, and d‐excess values were observed, with lower values during the rainy season and higher values during the dry season, highlighting the impact of changes in moisture sources and local meteorological conditions on seasonal shifts in δD, δ18O, and δ17O. While, mean Δ′17O values were higher in rainy season and lower in dry season. Notably, during rainy season, there is a negative correlation between monthly Δ′17O values and the RH of the vapor source area, as well as a positive correlation with d‐excess. Recalculated Δ′17O values based on RH of oceanic moisture source, are higher than the measured values for this period, indicating the contribution of terrigenous moisture to precipitation in SW China. Precipitation Δ′17O values provide a more precise reflection of changes in moisture source, continental recycling, and evapotranspiration processes that drive water cycling compared Integrating modeling works in future will facilitate the use of precipitation Δ′17O values to quantify the impact of different moisture source on precipitation.

Biomass burning in Peninsular Southeast Asia intensifies meteorological drought in Southwest China

Biomass burning in Peninsular Southeast Asia (BB–PSEA) affects the climate in downwind regions, especially precipitation (PRE) in southern China. However, the impact of BB–PSEA on the meteorological drought in Southwest China (SWC), where closes to PSEA and often occurs seasonal drought, have not been clear yet. We selected a severe drought event in SWC from January to April 2010 and conducted sensitivity simulations using WRF–Chem (Weather Research and Forecasting model coupled with Chemistry) to evaluate the impact of BB–PSEA on the meteorological drought in SWC. Comparisons with observations revealed that the model performed well in simulating the spatiotemporal evolution of the drought in SWC. BB–PSEA increased the drought severity by 0.01–0.75 levels, enlarged drought areas by about 10%, and prolonged the drought duration mainly by one month in SWC. The impact of BB–PSEA on the drought in SWC in March/April was almost tenfold that in January/February, due to the higher emissions of BB–PSEA in March/April. The mechanism that BB–PSEA influenced drought predominantly involved the reduction of PRE, potential evapotranspiration (PET), and moisture fluxes in SWC. BB–PSEA aerosols warmed the air at 600–800 hPa and cooled the air near the surface in SWC, which stabilized the atmosphere and suppressed PRE and reduced PET in SWC. BB–PSEA aerosols also increased the sea surface temperature in South China Sea and the geopotential heights in the north of the Bay of Bengal, where the moisture sources of SWC originated from. This perturbation reduced the moisture fluxes across the west and south boundaries of SWC, resulting in the reduction of the water vapor content and PRE in SWC. Through elucidating the impact of BB–PSEA on the drought in SWC, this study clarified how BB–PSEA affected the climate in the downwind region and provided new understanding for drought prediction in SWC.

Deep desert aquifers as an archive for Mid- to Late Pleistocene hydroclimate: An example from the southeastern Mediterranean

Many efforts have been made to illuminate the nature of past hydroclimates in semi-arid and arid regions, where current and future shifts in water availability have enormous consequences on human subsistence. Deep desert aquifers, where groundwater is stored for prolonged periods, might serve as a direct record of major paleo-recharge events. To date, groundwater-based paleoclimate reconstructions have mainly focused on a relatively narrow timescale (up to ∼40 kyr), limited by the relatively short half-life of the widely used radiocarbon (5.73 kyr). Here we demonstrate the usage of deep regional aquifers in the arid southeastern Mediterranean as a hydroclimate archive for earlier Mid-to-Late Pleistocene epochs. State-of-the-art dating tools, primarily the 81Kr radioisotope (t1/2 = 229 kyr), were combined with other atmosphere-derived tracers to illuminate the impact of four distinguishable wetter episodes over the past 400 kyr, with differences in climatic conditions and paleo-recharge locations. Variations in stable water isotope composition suggest moisture transport from more proximal (Mediterranean) and distal (Atlantic) sources to different parts of the region at distinct times. Large variability in the computed noble gas-based recharge temperature (NGT), ranging ~15–30 °C, cannot be explained by climate variations solely, and points to different recharge pathways, including geothermal heating in the deep unsaturated zone and recharge from high-elevation (colder) regions. The obtained groundwater record complements and enhances the interpretation of other terrestrial archives in the arid region, including a contribution of valuable information regarding the moisture source origin as reflected in the deuterium-excess values, which is unattainable from the common practice analysis of calcitic cave deposits. We conclude that similar applications in other deep (hundred-m-order) regional groundwater systems (e.g., the Sahara desert aquifers) can significantly advance our understanding of long-term (up to 1 Myr) paleo-hydroclimate in arid regions, including places where no terrestrial remnants, such as cave, lake, and spring sediments, are available.

Isotopic characteristics of extreme “dragon-boat water” rainfall between mid-May and mid-June in 2022 in Fuzhou, southeastern China

With global warming, the surge in torrential “dragon-boat water” (DBW) events during mid-May and mid-June, following the onset of the South China Sea summer monsoon (SCSSM), poses escalating threats to southern China through severe flooding and impacts on human livelihoods and socio-economic development. To better understand their fundamental mechanisms, we investigated extreme DBW rain events that occurred in southeastern China in 2022. Analysis of stable isotopes in precipitation samples collected in Fuzhou before and after SCSSM onset uncovered a significant decrease in δ18O values following monsoon onset, indicating intensified regional convective activity. This decrease is attributed to the seasonal variation in moisture sources, with water vapor originating from distant oceans after SCSSM onset contributing to increased Rayleigh distillation and subsequent δ18O reduction. A negative correlation between upstream rainfall and δ18O values, particularly at 96 h along the backward trajectory, indicates the influences of accumulative convective activities on precipitation isotopes along water vapor transport paths. Individual rain events typically exhibit characteristic “V” or “W” shapes in δ18O, with the lowest values mostly observed in stratiform zone, governed by microphysical processes, such as mesoscale subsidence, vapor deposition of ice particles, and rain re-evaporation below cloud-base. Notably, events with low δ18O values often coincide with low initial values, suggesting decreased vapor δ18O before precipitation due to accumulative convection or upstream rainout. Our findings elucidate the mechanisms driving the long-term changes in precipitation isotopes and their evolution during DBW events, enriching our understanding of the interplay between precipitation isotopes, large-scale convection, and microphysical processes.

Revisiting the global distribution of the exponent of the power-function complementary relationship of terrestrial evaporation: Insights from an isenthalpic index

The complementary relationship (CR) of evaporation is one of widely-used approaches in estimating terrestrial evapration (E). However, the determination of the parameter values in CR-based models remains a difficult task. This is especially true for the new power-function complementary relationship (PCR) model developed recently, in which the key parameter that accounts for the effect of moisture advection over the drying land, b, must be well calibrated with consideration of an approporiate physical basis. Here, by proposing a new isenthalpic index that can be used for determining b directly without resorting to any a priori information of global E, this study found that the resulting b values (median = 1.64, standard deviation = 0.73) are generally smaller and display a narrower range than those reported recently by Kim et al. (2024). When applied with monthly input variables of 124 FLUXNET stations, the gridded b values improve upon E estimates that employ either i) a standard value of b (=2), or; ii) a calibrated value (same for all stations). The global distribution of the gridded b values –in contrast to those obtained by Kim et al. (2024) –aligns with its physical interpretation: low values (1 < b < 2) where the effect of moisture advection is weak (i.e., permanently/periodically wet, humid regions or regions far away from any significant external moisture source) and high ones (b > 2) when strong (i.e., warm arid/semi arid regions near a sea or high mountains of abundant moisture). The gridded b values improve the calibration-free PCR that employs a constant b (=2) and a Priestley-Taylor coefficient linked to the wet-environment air temperature.

Ground‐Observed Snow Albedo Changes During Rain‐On‐Snow Events in Northern Alaska

AbstractRain‐on‐snow (ROS) events occur when rain falls on snowpack and can have substantial ecological and social impacts. During ROS events, liquid water in the snowpack can decrease the surface albedo, which contributes to the positive snow‐albedo feedback and further accelerates snowmelt. In a warming climate, the frequency and spatial coverage of ROS events are projected to increase in the high‐latitude regions, especially in northern Alaska. Multi‐year ground observations at two northern Alaska sites are utilized to evaluate 59 ROS events from 2012 to 2022. Results show that ROS events lead to dramatic snow albedo changes with a mean decline of −0.04 per day, which is considerably larger than the multi‐year mean of −0.005 in May and −0.008 in June. A snow albedo model is used to simulate the daily snow albedo changes due to snowpack liquid water content. The simulated impact of liquid water content accounts for only 10% of the observed snow albedo changes. In addition, composite synoptic conditions from reanalysis products reveal different moisture sources for ROS events. ROS events in May are associated with anomalous high pressure systems over the site and meridional transport of warm and moist air from lower latitudes. While the June synoptic conditions for ROS events show little deviation from the climatological mean and suggest local moisture contributions. ROS events in June show comparable snow albedo changes as in May despite the difference in moisture sources, which implies a prolonged impact of ROS events on rapid snow deterioration during late spring.

Highly Efficient, Flexible, and Self-Healable Moisture-Driven Energy Harvester Based on 2D Vanadium Pentoxide Nanosheets

The ubiquitous source of atmospheric moisture brought about a fascinating research avenue of extracting atmospheric water to generate sustainable electricity. Energy may be extracted from ambient moisture with obvious and substantial advantages. This point-of-use technology provides a decentralized alternative to meet the energy needs in isolated off-grid places. Unlike traditional energy generators which predominantly rely upon fossil fuel, moisture-induced energy generators can extract energy from moisture in a sustainable and eco-friendly way. Herein, we demonstrated a self-healable moist electric generator (MEG) based on vanadium pentoxide (V2O5) 2D nanosheet membranes. Lamellar membranes of V2O5 nanosheets have been shown to be excellent cation conductors and excellent materials for harvesting energy from ambient moisture. Ultra-thin 2D nanosheets of V2O5 was obtained by treatment of bulk V2O5 crystals with hydrogen peroxide. V2O5 nanosheet membrane was fabricated by vacuum-assisted filtration of 2D V2O5 nanosheets dispersion over a PTFE support membrane. The V2O5 membrane was easily peeled off from the support membrane on drying to obtain a flexible and freestanding V2O5 membrane. The V2O5 membrane consisting of percolated nanofluidic channels was sandwiched between a bottom solid copper foil and a perforated copper foil as the bottom electrode. The top electrode is perforated for exposure to atmospheric humidity. As the atmospheric water molecules come in contact with the V2O5 surface, an open-circuit voltage of 0.5 Volts and a short-circuit current of 0.3 microamperes is generated. The generated voltage and current is attributed to the preferential flow of cations through the V2O5 nanochannels. The exposed surface and edges of V2O5 nanosheets have a high negative surface charge which results in the splitting of water molecules into H3O+ and OH- ions. An electrical double layer (EDL) is established at the V2O5/water interface which selectively permits H3O+ ions through the channels. The mobile ions of the EDL transport through the nanofluidic channels creating a gradient between the two electrodes, resulting in a constant potential difference between the top and bottom electrodes which is harvested as electric current. The MEGs can be easily connected in parallel or series to enhance the current and voltage respectively. We demonstrate ten MEGs connected in series to power small electronic devices such as calculators and humidity meters. One of the key features of the V2O5 MEG is its ability to repair any physical damage to the active material owing to the water-assisted healing characteristics V2O5 membrane. Figure 1

Assessing target areas for precipitating moisture source analysis of extratropical cyclones: An analysis based on case studies

Extratropical cyclones (ECs) play an important role in precipitation generation at mid-latitudes. EC circulation involves multiple precipitation-generating structures, raising questions regarding the origin of their moisture uptake. Our study aimed to identify the origin of precipitation using a Lagrangian approach by targeting EC characteristics in different regions. To achieve this goal, we focused on the 28 most intense ECs that affected the Iberian Peninsula (IP) in winter, with a detailed analysis of three cases, namely, Daniel, Elsa and Fabien, which occurred in December 2019. Our EC masking methodology defines target regions using the radius, warm conveyor belt (WCB) footprint stages, and a square root spiral contour centred on the cyclone, fitted to the decreasing mean sea level pressure field. Our results revealed that variations in the water budget radial target regions are driven by the intensity of moisture uptake over the spatial distribution. Furthermore, the moisture uptake patterns of the WCB ascent and outflow footprints closely resemble those of the central areas due to their geographical proximity. In the integral WCB uptake framework, the moisture gained from initial ascending particles within the inflow footprints effectively accounts for contributions from remote sources. Despite the broader precipitation inclusion, the spiral shape maintains systematic and efficient cyclone moisture dynamics.

Local Evapotranspiration Is the Only Relevant Source of Moisture at the Onset of the Rainy Season in South America

The South American Monsoon System, which transports moisture from Amazonia to Central-West Brazil, is an important moisture source for the summer rainy season in this region. While local evapotranspiration also contributes to the atmospheric moisture supply, the balance between local and remote sources during the onset of the rainy season remains uncertain. Our research aimed to quantify the role of local evapotranspiration in initiating the rainy season in Central-West Brazil. By utilizing data from various sources, such as remote sensing (MODIS), modern reanalysis (ECMWF’s ERA5), and composite products of rainfall (CHIRPS), and analyzing them in a comparative way, we conclusively found that local evapotranspiration is the only relevant source of moisture to the atmosphere during the dry-to-wet season transition, preceding the establishment of the monsoon system.

Anomalous Water Vapor Circulation in an Extreme Drought Event of the Mid‐Reaches of the Lancang‐Mekong River Basin

AbstractThe middle reaches of the Lancang‐Mekong River Basin (M‐LMRB) experienced a record‐breaking drought event in 2019, resulting in significant economic losses of approximately 650 million dollars and affecting a population of 17 million. However, the anomalous circulation and transportation processes of water vapor, which may have played a crucial role in inducing the extreme drought, have not been fully studied. In this study, we analyze the water vapor circulation during the 2019 drought event using the land‐atmosphere water balance and a backward trajectory model for moisture tracking. Our results indicate that the precipitation in the M‐LMRB from May to October 2019 was only 71.9% of the long‐term climatological mean (1959–2021). The low precipitation during this drought event can be attributed to less‐than‐normal external water vapor supply. Specifically, the backward trajectory model reveals a decrease in the amount of water vapor transported from the Indian Ocean, the Bay of Bengal, and the Pacific Ocean, which are the main moisture sources for precipitation in the region. Comparing the atmospheric circulation patterns in 2019 with the climatology, we identify anomalous anticyclone conditions in the Bay of Bengal, anomalous westerlies in the Northeast Indian Ocean, and an anomalous cyclone in the Western Pacific Ocean, collectively facilitating a stronger export of water vapor from the region. Therefore, the dynamic processes played a more significant role than thermodynamic processes in contributing to the 2019 extreme drought event.

Drivers of seasonal rainfall variability over the Angolan and Namibian plateaus

AbstractSouthern Africa has been strongly affected by ongoing climate change in recent decades. Rainfall variability is modulated by regional patterns of moisture advection and convergence in the lower troposphere. Using reanalysis, ground and satellite‐based rainfall products and observations from 10 weather stations, we perform a synoptic and climatological analysis focussing on atmospheric circulation, moisture transport and their relationship with rainfall anomalies over the Angolan and Namibian Plateau region. Results clearly show that a stronger (weaker) Zambezi low level jet (LLJ) magnitudes are associated with above (below) normal rainfalls over the main Angolan and Namibian plateaus. With lower confidence, a stronger Limpopo LLJ may also lead to enhanced rainfall over Namibia and southeast Angola. The Zambezi LLJ moisture fluxes are moderately controlled by Mozambique Chanel Trough and Angola Low intensities, while the Limpopo LLJ intensities have very low influence from the Mozambique Chanel Trough and Angola Low, respectively. The Angola Low in its tropical phase is associated with deeper moisture convergence and stronger vertical velocities, leading to higher amounts of precipitable water within the air column, thus enhancing precipitation over the region. It is shown that the major moisture source of rainfall, which is advected to via the Zambezi LLJ, is the Indian Ocean. Meanwhile, the Atlantic Ocean plays a minor role. Given the current lack of observations and projected climate change, further research and investments are urgently needed in the region, for example, regarding the expansion of the surface data network.

Precipitation extremes in Ukraine from 1979 to 2019: climatology, large-scale flow conditions, and moisture sources

Precipitation extremes in Ukraine from 1979 to 2019: climatology, large-scale flow conditions, and moisture sources

Refined simple model of stable water isotopic content in central Antarctic precipitation including Oxygen 17 fractionation

Modeling the isotopic composition of atmospheric precipitation is an important tool for climatic, paleoclimatic and hydrological studies. This paper presents an improved simple model of the isotopic composition of precipitation in Central Antarctica. It differs from the previous version published by Salamatin et al. (2004) by 1) the included geochemical cycle of oxygen 17 and 2) the possibility of solving the inverse problem (i.e., finding the trajectory parameters that could form the isotopic composition of the precipitation observed at the end of the trajectory). The paper examines in detail the main tuning parameters of the model, among which the most important are the temperature and humidity in the moisture source, the “circulation parameter”, which takes into account the advection of vapor into the moisture source, the condensation temperature and the degree of air supersaturation with moisture in ice clouds. Based on the analysis of data on the isotopic composition (including “excess of oxygen 17”, 17O-xs) of water vapor in the surface layer of the atmosphere over the ocean and surface snow sampled along meridional profiles in East Antarctica, the optimal tuning of the model for calculating the isotopic composition of atmospheric precipitation at the Antarctic Vostok station was performed. In particular, it is shown that the temperature and humidity of the air in the moisture source are +17.4°C and 72%, respectively, and the condensation temperature is –41.3°C. The possibilities of using the model to analyze the isotopic composition of liquid precipitation falling on other continents are discussed. The final part of the paper discusses the limitations of the model. In particular, it is noted that the model does not take into account such processes as the evaporation of precipitation when it falls in arid conditions, mixing of trajectories, the influence of local sources of moisture, as well as the features of isotope fractionation during the evaporation of moisture from the continents.

Impacts of Dampness on Structural Stability of Public Secondary School Buildings in Adamawa State, Nigeria

This research assessed the impact of dampness on the structural stability of public secondary school buildings in Adamawa state. Dampness as it were is the infiltration of water through the structural elements (interior and exterior) of an edifice, wetness of structural elements through moisture rise by capillary, or extreme quantity of moisture contained in building materials or the building components (Agyekum, Ayakwa, Koranteng &amp; Adinyira, 2013a; Wilkowska, 2017). A percentage of building structures that deteriorate during wetness, dampness, or excessive moisture movements are perceived, visible, or measurable (Soldatova, Sansone, Stephens &amp; Shah, 2011). A building is described as being affected by dampness when there is moisture that is not wanted to a certain degree in the building than its water- retaining capability such that finishes and structural members are stained or discoloured and certain secondary elements are either upturned or lifted (Ishak, Che Ani, Akashah &amp;Kayan, 2013). The primary sources of moisture in buildings according to Sulaiman and Beithou (2011) are liquid water from precipitation or plumbing leaks; water vapour from the building exterior or activities/processes within the building; liquid and vapour from the soil adjoining a building; and moisture built-in with the materials of construction or brought in with goods and people. Young (2007) and Agyekum et al. (2013), categorise the primary sources of moisture into three types: penetration dampness, condensation, and rising dampness. Specifically, it; determined the common types of dampness and common causes of dampness, it also determined the extent of the impacts of dampness and suggested suitable procedures for treating the impact of dampness. A descriptive research design was adopted for the study. Four purposes and four research questions were raised to guide the study, the population for this study is Grade A public secondary schools in Adamawa State. Three sampling techniques were employed in this study, these are stratified sampling, purposive sampling, and simple random sampling. A checklist and a structured questionnaire were developed.

The detailed moisture transport structure in extreme precipitation on the Tibetan Plateau caused by storm over the Bay of Bengal

AbstractThe storms over the Bay of Bengal (BoB) often combine with the weather systems such as the South Branch Trough (SBT) and the West Pacific Subtropical High (WPSH) to transport plenty of moisture inducing extreme precipitation on the Tibetan Plateau (TP). Determining the fine moisture structures of storms helps understand mechanism of this kind of extreme precipitation. An extreme precipitation occurred on the TP influenced by storm Rashmi (2008). A Lagrangian approach is scrutinized the forward and backward moisture transport trajectories of Rashmi and the TP, respectively. The moisture source of this extreme precipitation is relatively clear, which comes from the collaborative influence of Rashmi with the southwest jet generated by the SBT and the WPSH. Utilizing a three‐dimensional K‐means clustering method devised in this study, the Rashmi's forward trajectories are classified into three categories, the particles ascending with the northward movement of Rashmi (45%), consistently below 1 km (37.5%), and rapidly ascending into the southwest jet stream (17.5%). Notably, 97.5%, 1.2%, and 91% of these categories impact the TP, respectively. The moisture transport structure of storm is verified by backward tracking of moisture over the TP. In addition, the three‐dimensional moisture trajectories classification method is recommended when trajectories suffer rapid altitude changes.