1. introduction: increasing urbanization and industrialization rate in developed and developing countries cities, such as tehran, has led to increased air pollution. todays, the prediction and estimation of air quality parameters in urban regions are important topics in environmental studies due to their effect on human health. measurement of air quality are widely used in air quality control p...

[1] A quantitative analysis of thermal orbits is developed and applied to modeled air and ground temperatures. Thermal orbits are phase-space representations of air and ground temperature relationships that are generated by plotting daily or monthly ground temperatures against air temperatures. Thermal orbits are useful descriptive tools that provide straightforward illustrations of air and gro...

An integrated perspective of permafrost dynamics is a key bridge between and global socioeconomic assessments. This study investigated the air temperature changes (1976–2020) among zones in Northern Hemisphere their potential impacts on permafrost. We found that continuous experienced faster warming than other regions. The freezing index declined 724°C-day while thawing increased only 166°C-day...

Cryogenic scanning electron microscopy (cryo-SEM), image analysis (IA) of SEM micrographs and X-ray microtomography (XMT) were used to obtain new information about the morphology of iron ore green pellets in this work. Cryo-SEM and freeze fracturing was used to observe entrapped air bubbles and arrangement of particles around the bubbles and in the matrix of wet green pellets. The observations ...

Seasonal changes in freezing stress resistance of needles of red pine (Pinus resinosa Ait.) and Austrian pine (Pinus nigra Arnold) trees were measured by an electrolyte leakage method and by visual observation. During most of the year, freezing stress resistance determined by the two methods gave similar results. The electrolyte leakage method provided a good estimate of seasonal changes in fre...

We have used NCEP/NCAR Reanalysis data and a Northern Hemisphere snow cover data set to analyze changes in freezing level heights and snow cover for the past three to five decades. All the major continental mountain chains exhibit upward shifts in the height of the freezing level surface. The pattern of these changes is generally consistent with changes in snow cover, both over the course of th...

Introduction Conclusions References Tables Figures Back Close Abstract Introduction Conclusions References Tables Figures Back Close Abstract Recent field observations suggest that the fraction of organics containing aerosol particles in ice cloud particles is diminished when compared to the background aerosol prior to freezing. In this work, we use model calculations to investigate possible ca...

Freeze-thaw events can affect plant hydraulics by inducing embolism. This study analyzed the effect of temperature during the freezing process on hydraulic conductivity and ultrasonic emissions (UE). Stems of 10 angiosperms were dehydrated to a water potential at 12% percentage loss of hydraulic conductivity (PLC) and exposed to freeze-thaw cycles. The minimal temperature of the frost cycle cor...

*The 'thaw-expansion hypothesis' postulates that xylem embolism is caused by the formation of gas bubbles on freezing and their expansion on thawing. We evaluated the hypothesis using centrifuge experiments and ultrasonic emission monitoring in Pinus contorta. *Stem samples were exposed to freeze-thaw cycles at varying xylem pressure (P) in a centrifuge before the percentage loss of hydraulic c...