scholarly journals Ambient conditions prevailing during hail events in central Europe

2020 ◽  
Vol 20 (6) ◽  
pp. 1867-1887 ◽  
Author(s):  
Michael Kunz ◽  
Jan Wandel ◽  
Elody Fluck ◽  
Sven Baumstark ◽  
Susanna Mohr ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Lapse Rate ◽  
Storm Tracks ◽  
Synoptic Scale ◽  
Ambient Conditions ◽  
Convective Storm ◽  
Convective Storms ◽  
Investigation Area ◽  
Severe Thunderstorms ◽  
Eyewitness Reports

Abstract. Around 26 000 severe convective storm tracks between 2005 and 2014 have been estimated from 2D radar reflectivity for parts of Europe, including Germany, France, Belgium, and Luxembourg. This event set was further combined with eyewitness reports, environmental conditions, and synoptic-scale fronts based on the ERA-Interim (ECMWF Reanalysis) reanalysis. Our analyses reveal that on average about a quarter of all severe thunderstorms in the investigation area were associated with a front. Over complex terrains, such as in southern Germany, the proportion of frontal convective storms is around 10 %–15 %, while over flat terrain half of the events require a front to trigger convection. Frontal storm tracks associated with hail on average produce larger hailstones and have a longer track. These events usually develop in a high-shear environment. Using composites of environmental conditions centered around the hailstorm tracks, we found that dynamical proxies such as deep-layer shear or storm-relative helicity become important when separating hail diameters and, in particular, their lengths; 0–3 km helicity as a dynamical proxy performs better compared to wind shear for the separation. In contrast, thermodynamical proxies such as the lifted index or lapse rate show only small differences between the different intensity classes.

scholarly journals Ambient conditions prevailing during hail events in central Europe

2020 ◽  
Author(s):  
Michael Kunz ◽  
Jan Wandel ◽  
Elody Fluck ◽  
Sven Baumstark ◽  
Susanna Mohr ◽  
...  
Keyword(s):  
Wind Shear ◽  
Deep Layer ◽  
Lapse Rate ◽  
Synoptic Scale ◽  
Ambient Conditions ◽  
Convective Storm ◽  
Convective Storms ◽  
Investigation Area ◽  
Severe Thunderstorms ◽  
Eyewitness Reports

Abstract. Around 26 000 severe convective storm tracks between 2005 and 2014 have been estimated from 2D radar reflectivity for parts of Europe, including Germany, France, Belgium, and Luxembourg. This event-set was further combined with eyewitness reports, convection-related parameters from ERA-Interim reanalysis and synoptic-scale fronts based on the same reanalysis. Our analyses reveal that about a quarter of all severe thunderstorms in the investigation area were associated with a front. Over complex terrains, such as in southern Germany, the proportion of frontal convective storms is around 10–15 %, while over flat terrain half of the events require a front to trigger convection. Frontal hailstorms on average produce larger hailstones and have a longer track. These events usually develop in a high-shear environment. Using composites of environmental conditions centered around the hailstorm tracks, we found that dynamical proxies such as deep-layer shear or storm-relative helicity become important when separating hail diameters and, in particular, their lengths; 0–3 km helicity as a dynamical proxy performs better compared to wind shear for the separation. In contrast, thermodynamical proxies such as Lifted Index or lapse rate show only small differences between the different intensity classes.

scholarly journals Ecological specialization, variability in activity patterns and response to environmental change

2018 ◽  
Vol 14 (6) ◽  
pp. 20180115 ◽  
Author(s):  
Talisin T. Hammond ◽  
Rupert Palme ◽  
Eileen A. Lacey
Keyword(s):  
Environmental Change ◽  
Environmental Conditions ◽  
Phenotypic Variability ◽  
Activity Patterns ◽  
Temporal Patterns ◽  
Past Century ◽  
Ambient Conditions ◽  
Ecological Specialization ◽  
Sympatric Populations ◽  
Individual Level

Differences in temporal patterns of activity can modulate the ambient conditions to which organisms are exposed, providing an important mechanism for responding to environmental change. Such differences may be particularly relevant to ecological generalists, which are expected to encounter a wider range of environmental conditions. Here, we compare temporal patterns of activity for partially sympatric populations of a generalist (the lodgepole chipmunk, Tamias speciosus ) and a more specialized congener (the alpine chipmunk, Tamias alpinus ) that have displayed divergent responses to the past century of environmental change. Although mean activity budgets were similar between species, analyses of individual-level variation in locomotion revealed that T. alpinus exhibited a narrower range of activity patterns than T . speciosus . Further analyses revealed that T. alpinus was more active earlier in the day, when temperatures were cooler, and that activity patterns for both species changed with increased interspecific co-occurrence. These results are consistent with the greater responsiveness of T. alpinus to changes in environmental conditions. In addition to highlighting the utility of accelerometers for collecting behavioural data, our findings add to a growing body of evidence, suggesting that the greater phenotypic variability displayed by ecological generalists may be critical to in situ responses to environmental change.

scholarly journals Thermally induced torpor in fullterm lizard embryos synchronizes hatching with ambient conditions

2006 ◽  
Vol 2 (3) ◽  
pp. 415-416 ◽  
Author(s):  
Rajkumar Radder ◽  
Richard Shine
Keyword(s):  
Environmental Conditions ◽  
Low Temperatures ◽  
Access To Information ◽  
Ambient Conditions ◽  
Thermally Induced ◽  
Ambient Temperatures ◽  
Ground Conditions ◽  
Soil Temperatures ◽  
Bassiana Duperreyi ◽  
Do So

Eggs inside an underground nest have limited access to information about above-ground conditions that might affect the survival of emerging hatchlings. Our measurements of heart rates of embryos inside the intact eggs of montane lizards ( Bassiana duperreyi , Scincidae) show that low temperatures induce torpor in fullterm embryos, but do not do so during earlier embryogenesis or later, post-hatching. Because above-ground conditions affect soil temperatures, this stage-dependent torpor effectively restricts hatching to periods of high ambient temperatures above ground. Torpor thus can function not only to synchronize activity with suitable environmental conditions during post-hatching life (as reported for many species), but also can occur in embryos, to synchronize hatching with above-ground conditions that facilitate successful emergence from the nest.

scholarly journals Radar Z–RRelationship for Summer Monsoon Storms in Arizona

2005 ◽  
Vol 20 (4) ◽  
pp. 672-679 ◽  
Author(s):  
Efrat Morin ◽  
Robert A. Maddox ◽  
David C. Goodrich ◽  
Soroosh Sorooshian
Keyword(s):  
Hydrologic Model ◽  
Storm Events ◽  
Convective Storm ◽  
Convective Storms ◽  
Discharge Rates ◽  
Wide Range ◽  
Gauge Data ◽  
R Relation ◽  
Initial Results ◽  
Good Agreement

Abstract Radar-based estimates of rainfall rates and accumulations are one of the principal tools used by the National Weather Service (NWS) to identify areas of extreme precipitation that could lead to flooding. Radar-based rainfall estimates have been compared to gauge observations for 13 convective storm events over a densely instrumented, experimental watershed to derive an accurate reflectivity–rainfall rate (i.e., Z–R) relationship for these events. The resultant Z–R relationship, which is much different than the NWS operational Z–R, has been examined for a separate, independent event that occurred over a different location. For all events studied, the NWS operational Z–R significantly overestimates rainfall compared to gauge measurements. The gauge data from the experimental network, the NWS operational rain estimates, and the improved estimates resulting from this study have been input into a hydrologic model to “predict” watershed runoff for an intense event. Rainfall data from the gauges and from the derived Z–R relation produce predictions in relatively good agreement with observed streamflows. The NWS Z–R estimates lead to predicted peak discharge rates that are more than twice as large as the observed discharges. These results were consistent over a relatively wide range of subwatershed areas (4–148 km2). The experimentally derived Z–R relationship may provide more accurate radar estimates for convective storms over the southwest United States than does the operational convective Z–R used by the NWS. These initial results suggest that the generic NWS Z–R relation, used nationally for convective storms, might be substantially improved for regional application.

scholarly journals A 6-yr Climatology of Fronts Affecting Helsinki, Finland, and Their Boundary Layer Structure

2013 ◽  
Vol 52 (9) ◽  
pp. 2106-2124 ◽  
Author(s):  
Victoria A. Sinclair
Keyword(s):  
Boundary Layer ◽  
Temperature Change ◽  
Frontal Zone ◽  
Layer Structure ◽  
Time Of Day ◽  
Lapse Rate ◽  
Maximum Temperature ◽  
Synoptic Scale ◽  
Boundary Layer Structure ◽  
Cold Fronts

AbstractA 6-yr climatology of the frequency, characteristics, and boundary layer structure of synoptic-scale fronts in Helsinki, Finland, was created using significant weather charts and observations from a 327-m-tall mast and from the Station for Measuring Ecosystem–Atmosphere Relationships III. In total, 855 fronts (332 cold fronts, 236 warm fronts, and 287 occluded fronts) affected Helsinki during the 6-yr period, equating to one front every 2.6 days. Seasonal and diurnal cycles were observed, with frontal frequency peaking during the cold season and during daytime. Composites of warm and cold fronts were developed to provide observationally based conceptual models of the low-level structure of fronts at the end of the North Atlantic Ocean storm track. The composite warm front displays a temperature increase of 4.0°C; a broad, forward-tilting frontal zone; and prolonged, weak-to-moderate precipitation. The composite cold front is characterized by a temperature decrease of 4.4°C, a narrow and slightly rearward-tilting frontal zone, and moderate precipitation collocated with the surface front. Relationships between frontal characteristics and the direction from which fronts approached, the season, time of day, prefrontal boundary layer lapse rate, and the location of the wind shift relative to the thermal gradient were investigated. The prefrontal lapse rate was the single most important variable in determining the temperature change, the height of the maximum temperature change, and the near-surface tilt of both warm and cold fronts. This result demonstrates the interaction between boundary layer and synoptic-scale processes that must be captured by numerical weather prediction models to accurately forecast surface fronts.

scholarly journals Quality Deterioration of Commercial Bean (Phaseolus vulgaris) Seeds Stored under Contrasting Environmental Conditions in Sri Lanka

2020 ◽  
Vol 8 (1) ◽  
pp. 33-44
Author(s):  
R.A.I.S. Ariyarathna ◽  
S.L. Weerasena ◽  
C.K. Beneragama
Keyword(s):  
Sri Lanka ◽  
Low Temperature ◽  
Environmental Conditions ◽  
Seed Quality ◽  
Storage Period ◽  
Fluorescence Analysis ◽  
Quality Parameters ◽  
Full Potential ◽  
Ambient Conditions ◽  
Field Emergence

Bean is a popular vegetable grown in most parts of Sri Lanka. Farmers and home gardeners purchase seeds in packeted form retail outlets. However, quality problems are frequently reported, especially on low field germination. Quality parameters namely, percentage germination, field emergence, seedling length, vigour index and chlorophyll fluorescence analysis were used to determine the effect of different storage environmental conditions on seed longevity of two bean varieties during a two-year storage period, 2016 to 2018. Seeds in triple-laminated packets stored in four contrasting conditions; low temperature storage conditions (Tem. 5oC, 65% RH); three geo-environmental conditions namely, Gannoruwa (mid country wet zone), Kundasale (mid country intermediate zone), and Mahailuppallama (low country dry zone) showed varied behavior in seed quality parameters respective of the variety. It was apparent that germination test alone does not represent the full potential of field emergence. Results of the present study revealed that when field emergence and vigour are also taken in to account, both varieties of bean seeds can be stored under ambient conditions at Gannoruwa, Kundasale or MahaIlluppallama for a maximum period of 12 months, without compromising the seed quality. The seeds stored under low temperature conditions (i.e. 5 °C), maintained the seed germination over 75% for a period of 24 months.  

scholarly journals Observations of Hail–Wind Ratios from Convective Storm Reports across the Continental United States

2020 ◽  
Vol 35 (2) ◽  
pp. 635-656 ◽  
Author(s):  
Matthew J. Bunkers ◽  
Steven R. Fleegel ◽  
Thomas Grafenauer ◽  
Chauncy J. Schultz ◽  
Philip N. Schumacher
Keyword(s):  
United States ◽  
Late Summer ◽  
Weather Forecast ◽  
Eastern United States ◽  
Convective Storm ◽  
Convective Storms ◽  
Warm Summer ◽  
Central United States ◽  
Spatiotemporal Analyses ◽  
Convective Mode

Abstract The objective of this study is to provide guidance on when hail and/or wind is climatologically most likely (temporally and spatially) based on the ratio of severe hail reports to severe wind reports, which can be used by National Weather Forecast (NWS) forecasters when issuing severe convective warnings. Accordingly, a climatology of reported hail-to-wind ratios (i.e., number of hail reports divided by the number of wind reports) for observed severe convective storms was derived using U.S. storm reports from 1955 to 2017. Owing to several temporal changes in reporting and warning procedures, the 1996–2017 period was chosen for spatiotemporal analyses, yielding 265 691 hail and 294 449 wind reports. The most notable changes in hail–wind ratios occurred around 1996 as the NWS modernized and deployed new radars (leading to more hail reports relative to wind) and in 2010 when the severe hail criterion increased nationwide (leading to more wind reports relative to hail). One key finding is that hail–wind ratios are maximized (i.e., relatively more hail than wind) during the late morning through midafternoon and in the spring (March–May), with geographical maxima over the central United States and complex/elevated terrain. Otherwise, minimum ratios occur overnight, during the late summer (July–August) as well as November–December, and over the eastern United States. While the results reflect reporting biases (e.g., fewer wind than hail reports in low-population areas but more wind reports where mesonets are available), meteorological factors such as convective mode and cool spring versus warm summer environments also appear associated with the hail–wind ratio climatology.

scholarly journals Conditioning in the promotion and uniformization of Umbu seed germination

2018 ◽  
Vol 40 (1) ◽  
Author(s):  
Renato Teo Barros ◽  
Cibele Chalita Martins ◽  
Francisco Elder Carlos Bezerra Pereira ◽  
Givanildo Zildo da Silva
Keyword(s):  
Electrical Conductivity ◽  
Seed Germination ◽  
Water Content ◽  
Environmental Conditions ◽  
Seed Quality ◽  
Germination Rate ◽  
Ambient Conditions ◽  
Germination Test ◽  
Mean Germination Time ◽  
Cold Chamber

Abstract Seed dormancy may decrease during storage and some environmental conditions may accelerate this process. The aim of this work was to determine efficient techniques to condition umbu seeds in order to promote and standardize their germination. Seeds were stored for 180 days in paper bags kept in five ambient conditions: laboratory (25 ºC and 55% RH); warm oven (40 °C and 53% RH); hot oven (50 °C and 49% RH); dry chamber (18 °C and 65% RH) and cold chamber (10 °C and 65% RH). Seed quality was evaluated every 60 days by means of the following tests and determinations: water content; germination test (25 °C and 55% RH, weekly evaluated up to 91 days after sowing); first count test (14 days); germination rate index; mean germination time and electrical conductivity. The conditioning of umbu seeds in laboratory, or in warm oven (40 ºC) used efficient techniques to promote and standardize germination; under these conditions, after six months of storage, germination increased from 31% to 84 and 74%, respectively.

scholarly journals Centreline and cross-glacier air temperature variability on an Alpine glacier: assessing temperature distribution methods and their influence on melt model calculations

2017 ◽  
Vol 63 (242) ◽  
pp. 973-988 ◽  
Author(s):  
THOMAS E. SHAW ◽  
BEN W. BROCK ◽  
ÁLVARO AYALA ◽  
NICK RUTTER ◽  
FRANCESCA PELLICCIOTTI
Keyword(s):  
Temperature Distribution ◽  
Air Temperature ◽  
Temporal Distribution ◽  
Temperature Variability ◽  
Lapse Rate ◽  
Balance Model ◽  
Model Parameters ◽  
Ambient Conditions ◽  
Distribution Models ◽  
Model Calculations

ABSTRACTThe spatio-temporal distribution of air temperature over mountain glaciers can demonstrate complex patterns, yet it is often represented simplistically using linear vertical temperature gradients (VTGs) extrapolated from off-glacier locations. We analyse a network of centreline and lateral air temperature observations at Tsanteleina Glacier, Italy, during summer 2015. On average, VTGs are steep (<−0.0065 °C m−1), but they are shallow under warm ambient conditions when the correlation between air temperature and elevation becomes weaker. Published along-flowline temperature distribution methods explain centreline observations well, including warming on the lower glacier tongue, but cannot estimate lateral temperature variability. Application of temperature distribution methods improves simulation of melt rates (RMSE) in an energy-balance model by up to 36% compared to the environmental lapse rate extrapolated from an off-glacier station. However, results suggest that model parameters are not easily transferable to glaciers with a small fetch without recalibration. Such methods have potential to improve estimates of temperature across a glacier, but their parameter transferability should be further linked to the glacier and atmospheric characteristics. Furthermore, ‘cold spots’, which can be >2°C cooler than expected for their elevation, whose occurrence is not predicted by the temperature distribution models, are identified at one-quarter of the measurement sites.

scholarly journals Assessment of the Effect of Environmental Conditions on Rotorcraft Pollutant Emissions at Mission Level

2017 ◽  
Author(s):  
Jesus Ortiz-Carretero ◽  
Alejandro Castillo Pardo ◽  
Vassilios Pachidis ◽  
Ioannis Goulos
Keyword(s):  
Environmental Conditions ◽  
Engine Performance ◽  
Pollutant Emissions ◽  
Civil Aviation ◽  
Ambient Conditions ◽  
Engine Operation ◽  
Helicopter Rotors ◽  
Helicopter Flight ◽  
Fuel Burn

It is anticipated that the contribution of rotorcraft activities to the environmental impact of civil aviation will increase in the forthcoming future. Due to their versatility and robustness, helicopters are often operated in harsh environments with extreme ambient conditions and dusty air. These severe conditions affect not only the engine operation but also the performance of helicopter rotors. This impact is reflected in the fuel burn and pollutants emitted by the helicopter during a mission. The aim of this paper is to introduce an exhaustive methodology to quantify the influence of the environment in the mission fuel consumption and the associated emissions of nitrogen oxides (NOx). An Emergency Medical Service (EMS) and a Search and Rescue (SAR) mission were used as a case study to simulate the effects of extreme temperatures, high altitude and compressor degradation on a representative Twin-Engine Medium (TEM) weight helicopter, the Sikorsky UH-60A Black Hawk. A simulation tool for helicopter mission performance analysis developed and validated at Cranfield University was employed. This software comprises different modules that enable the analysis of helicopter flight dynamics, powerplant performance and exhaust emissions over a user defined flight path profile. The results obtained show that the environmental effects on mission fuel and emissions are mainly driven by the modification of the engine performance for the particular missions simulated. Fluctuations as high as 12% and 40% in mission fuel and NOx emissions, respectively, were observed under the environmental conditions simulated in the present study.

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