scholarly journals Ice in caves and its effect on thermal inversion and permafrost in the case of the Velika ledena jama v Paradani, Smrekova draga and neighbouring dolines

2021 ◽  
Vol 50 (2-3) ◽  
Author(s):  
Andrej Mihevc
Keyword(s):  
Sea Level ◽  
Surrounding Area ◽  
Cold Air ◽  
Thermal Inversion ◽  
Average Temperature ◽  
Cave Entrance ◽  
Air Temperatures ◽  
Winter Cold ◽  
Air Circulation ◽  
Similar Development

In the Velika ledena jama v Paradani, in the karstic blowholes on the slopes of Smrekova draga and in the nearby dolines I measured and interpreted air temperatures and the effect of the summer outflow of cold air from them into the surrounding area. In winter, cold air enters the cave, radically cooling the entrance part of the cave, where for this reason there is permanent cave ice. The summertime circulation is reversed: emerging from the inner part of cave, which has an average temperature of around 4° C, is air which only when it transits through the sub-cooled entrance part is then cooled to around 1° C. This air comes to the surface and in the hollow at the cave entrance maintains a distinct thermal inversion during the warm part of the year. There is a similar air circulation and similar development of annual temperatures observed at the vents, where cave air emerges through rubble spread over cave entrances on slopes or at the bottom of dolines. The stable summer air temperatures of around 1° C in the vents where I conducted measurements indicate that underneath them there is also permafrost or sub-cooled rock and permanent ice. This is created and preserved, just like in the caves, due to the advection of cold air in winter. In Trnovski gozd, such karstic permafrost is found at an altitude of 1,100 m above sea level. The outflow of cold air from the vents in the summer, just like inside the cave, causes a distinct thermal inversion in dolines on the surface.

Could climate engineering save the Greenland Ice Sheet?

2016 ◽  
Author(s):  
Patrick J. Applegate ◽  
K. Keller
Keyword(s):  
Sea Level Rise ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Sea Level ◽  
Computer Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Upper Atmosphere ◽  
Climate Engineering ◽  
Air Temperatures

Engineering the climate through albedo modification (AM) could slow, but probably would not stop, melting of the Greenland Ice Sheet. Albedo modification is a technology that could reduce surface air temperatures through putting reflective particles into the upper atmosphere. AM has never been tested, but it might reduce surface air temperatures faster and more cheaply than reducing greenhouse gas emissions. Some scientists claim that AM would also prevent or reverse sea-level rise. But, are these claims true? The Greenland Ice Sheet will melt faster at higher temperatures, adding to sea-level rise. However, it's not clear that reducing temperatures through AM will stop or reverse sea-level rise due to Greenland Ice Sheet melting. We used a computer model of the Greenland Ice Sheet to examine its contributions to future sea level rise, with and without AM. Our results show that AM would probably reduce the rate of sea-level rise from the Greenland Ice Sheet. However, sea-level rise would likely continue even with AM, and the ice sheet would not regrow quickly. Albedo modification might buy time to prepare for sea-level rise, but problems could arise if policymakers assume that AM will stop sea-level rise completely.

scholarly journals Seasonal Influence of Insolation on Fine-Resolved Air Temperature Variation and Snowmelt

2014 ◽  
Vol 53 (2) ◽  
pp. 323-332 ◽  
Author(s):  
Nikki Vercauteren ◽  
Steve W. Lyon ◽  
Georgia Destouni
Keyword(s):  
Solar Radiation ◽  
Snow Cover ◽  
Eastern Coast ◽  
Seasonal Influence ◽  
Near Surface ◽  
Average Temperature ◽  
Monthly Average ◽  
Air Temperatures ◽  
Low Performance ◽  
Snow Cover Duration

AbstractThis study uses GIS-based modeling of incoming solar radiation to quantify fine-resolved spatiotemporal responses of year-round monthly average temperature within a field study area located on the eastern coast of Sweden. A network of temperature sensors measures surface and near-surface air temperatures during a year from June 2011 to June 2012. Strong relationships between solar radiation and temperature exhibited during the growing season (supporting previous work) break down in snow cover and snowmelt periods. Surface temperature measurements are here used to estimate snow cover duration, relating the timing of snowmelt to low performance of an existing linear model developed for the investigated site. This study demonstrates that linearity between insolation and temperature 1) may only be valid for solar radiation levels above a certain threshold and 2) is affected by the consumption of incoming radiation during snowmelt.

scholarly journals Mathematical modeling and determination of thermodynamic properties of jabuticaba peel during the drying process

2016 ◽  
Vol 20 (6) ◽  
pp. 576-580 ◽  
Author(s):  
Cristian F. Costa ◽  
Paulo C. Corrêa ◽  
Jaime D. B. Vanegas ◽  
Fernanda M. Baptestini ◽  
Renata C. Campos ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Drying Process ◽  
Drying Temperature ◽  
Air Temperatures ◽  
Nutritional Qualities ◽  
Forced Air ◽  
Air Circulation ◽  
Best Fit

ABSTRACT Jabuticaba is a fruit native of Brazil and, besides containing many nutritional qualities, it also has a good field for use in products such as flour for cakes and biscuits, juice, liqueur, jelly and others. This study aimed to model the drying kinetics and determine the thermodynamic properties of jabuticaba peel at different drying air temperatures. Ripe fruits of jabuticaba (Myrciaria jaboticaba) were collected and pulped manually. Drying was carried out in a forced-air circulation oven with a flow of 5.6 m s-1 at temperatures of 40, 50, 60 and 70 °C. Six mathematical models commonly used to represent the drying process of agricultural products were fitted to the experimental data. The Arrhenius model was used to represent the drying constant as a function of temperature. The Midilli model showed the best fit to the experimental data of drying. The drying constant increased with the increment in drying temperature and promoted an activation energy of 37.29 kJ mol-1. Enthalpy and Gibbs free energy decreased with the increase in drying temperature, while entropy decreased and was negative.

scholarly journals Exceptional retreat of Novaya Zemlya's marine-terminating outlet glaciers between 2000 and 2013

2017 ◽  
Author(s):  
J. Rachel Carr ◽  
Heather Bell ◽  
Rebecca Killick ◽  
Tom Holt
Keyword(s):  
Sea Ice ◽  
Sea Level Rise ◽  
Sea Level ◽  
Remotely Sensed ◽  
Glacier Retreat ◽  
Remotely Sensed Data ◽  
Novaya Zemlya ◽  
The Past ◽  
Air Temperatures ◽  
The Impact

Abstract. Novaya Zemlya (NVZ) has experienced rapid ice loss and accelerated marine-terminating glacier retreat during the past two decades. However, it is unknown whether this retreat is exceptional longer-term and/or whether it has persisted since 2010. Investigating this is vital, as dynamic thinning may contribute substantially to ice loss from NVZ, but is not currently included in sea level rise predictions. Here, we use remotely sensed data to assess controls on NVZ glacier retreat between the 1973/6 and 2015. Glaciers that terminate into lakes or the ocean receded 3.5 times faster than those that terminate on land. Between 2000 and 2013, retreat rates were significantly higher on marine-terminating outlet glaciers than during the previous 27 years, and we observe widespread slow-down in retreat, and even advance, between 2013 and 2015. There were some common patterns in the timing of glacier retreat, but the magnitude varied between individual glaciers. Rapid retreat between 2000–2013 corresponds to a period of significantly warmer air temperatures and reduced sea ice concentrations, and to changes in the NAO and AMO. We need to assess the impact of this accelerated retreat on dynamic ice losses from NVZ, to accurately quantify its future sea level rise contribution.

scholarly journals Firn temperature and meltwater refreezing in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland

1993 ◽  
Vol 159 ◽  
pp. 109-114
Author(s):  
R.J Braithwaite
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
International Project ◽  
Sea Level Changes ◽  
West Greenland ◽  
Degree Day ◽  
Air Temperatures ◽  
Surface Melt ◽  
High Degree

Firn temperatures and meltwater refreezing are studied in the lower accumulation area of the Greenland ice sheet as part of an international project on sea level changes. In the study area, 1440–1620 m a.s.l., meltwater penetrates several metres into the firn and refreezes, warming the firn by 5–7°C compared with annual air temperatures. This firn warming is closely related to surface melt which can be estimated by several methods. A relatively high degree-day factor is needed to account for the melt rates found.

scholarly journals Simulations of a cold-air pool associated with elevated wintertime ozone in the Uintah Basin, Utah

2014 ◽  
Vol 14 (11) ◽  
pp. 15953-16000 ◽  
Author(s):  
E. M. Neemann ◽  
E. T. Crosman ◽  
J. D. Horel ◽  
L. Avey
Keyword(s):  
Boundary Layer ◽  
Snow Cover ◽  
Layer Structure ◽  
Inversion Layer ◽  
Cloud Microphysics ◽  
Photochemical Reactions ◽  
Near Surface ◽  
Cold Air ◽  
Air Temperatures ◽  
Uintah Basin

Abstract. Numerical simulations are used to investigate the meteorological characteristics of the 1–6 February 2013 cold-air pool in the Uintah Basin, Utah, and the resulting high ozone concentrations. Flow features affecting cold-air pools and air quality in the Uintah Basin are studied, including: penetration of clean air into the basin from across the surrounding mountains, elevated easterlies within the inversion layer, and thermally-driven slope and valley flows. The sensitivity of the boundary layer structure to cloud microphysics and snow cover variations are also examined. Ice-dominant clouds enhance cold-air pool strength compared to liquid-dominant clouds by increasing nocturnal cooling and decreasing longwave cloud forcing. Snow cover increases boundary layer stability by enhancing the surface albedo, reducing the absorbed solar insolation at the surface, and lowering near-surface air temperatures. Snow cover also increases ozone levels by enhancing solar radiation available for photochemical reactions.

scholarly journals 200-Hundred Year Climate Record From Antarctic Peninsula

1990 ◽  
Vol 14 ◽  
pp. 353-353
Author(s):  
D.A. Peel ◽  
R. Mulvaney
Keyword(s):  
Antarctic Peninsula ◽  
Ice Core ◽  
Weddell Sea ◽  
Average Temperature ◽  
Air Temperatures ◽  
Isotope Record ◽  
James Ross Island ◽  
Weather Stations ◽  
Isotopic Records ◽  
Reported Data

A stable isotope record extending back to 1795 is now available from Dolleman Island (70°35.2′S, 60°55.5′W), a small ice rise on the Weddell Sea coast of Antarctic Peninsula. An accurate chronology has been achieved by combined stratigraphic analysis of clear seasonal cycles in δ18O and excess SO4. Previous work (Peel and others, 1988) has shown that, since 1947, there is generally a satisfactory correlation between interannual variations in δ18O and air temperature (T) as recorded at weather stations in various parts of the region, suggesting that the derived δ18O/T ratio may be used to reconstruct air temperatures for the earlier period.Taken together with previously-reported data (Aristarain and others, 1986) for an ice core from James Ross Island it is now possible to propose a regional climatic signal for the Weddell Sea coastal sector of the region. The most striking feature is a broad maximum in δ18O for the mid-19th century, implying decadal average temperature at least as high as the present. This contrasts with available evidence from elsewhere in the southern hemisphere which suggest that this period was cooler than today. Tentative explanations for the anomaly are proposed based on evidence for a period (1974–80), where climatic shifts are clearly amplified in the isotopic records.

scholarly journals DESIGN AND STUDY OF DIMENSIONAL PARAMETERS INFLUENCE ON VORTEX TUBE BEHAVIOR

2019 ◽  
Vol 18 (2) ◽  
pp. 13
Author(s):  
F. P. Branco ◽  
E. D. Buchelt ◽  
F. M. Barbosa ◽  
B. P. Rosa ◽  
D. J. Laporte
Keyword(s):  
Vortex Tube ◽  
Tube Diameter ◽  
Compressed Air ◽  
Tube Length ◽  
Electronic Systems ◽  
Machining Processes ◽  
Cold Air ◽  
Air Temperatures ◽  
Small Influence ◽  
Dimensional Parameters

Vortex tube is a thermodynamic device, with no moving parts, applied to separate hot and cold air from compressed air injected into the tube. It has many applications in the industry, for example, among others, it can be mentioned electronic systems cooling, machining processes cooling and environmental chambers. This paper presents the design and tube dimensioning based on parameters and data found in the literature. Therefore, a prototype has been made and tested, which allowed the understanding of the influence of internal tube diameter and width on the hot and cold air temperatures while submitted to compressed air with pressure varying from 1 to 2.5bar. Results of tested configurations indicates that the relation between tube length and diameter (L/D) has small influence on vertex tube behavior, meanwhile, 3/8” tube diameter shows lowest temperatures on cold flow (-6.5°C, -8.0°C and -8.5°C) and higher COP (≈ 0.15).

Determination of Brittle Point of Rubber Materials in Cold Air

1944 ◽  
Vol 17 (3) ◽  
pp. 751-756
Author(s):  
C. K. Chatten ◽  
S. A. Eller ◽  
T. A. Werkenthin
Keyword(s):  
Ambient Air ◽  
Cold Air ◽  
Air Temperatures ◽  
Brittle Point ◽  
Made In

Abstract The method described herein for determining brittle point is relatively simple, and the results are indicative of the ability of the material to withstand impact combined with bending. It is believed that this combination will more correctly evaluate brittle point than a bent loop test or other moderate flexing tests. If the material is exposed to low ambient air temperatures in service, then tests to determine brittle point should be made in cold air and not in an immersion bath. Appreciable differences in brittle point are obtained by judicious modifications in compounding ingredients of Buna-N and chloroprene synthetic rubbers.

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