the aim of this research is recognizing synoptic patterns of the level 500 hp occurrence of late spring freezes over kurdistan province during 1965-2005. after determining freeze temporal-spatial threshold, 22 freezing days spreading over the region were extracted. then, level 500 hp height data located in a scope of 25-60 northern latitude and 30-60 eastern longitude was formulated as an s-mod...

in this research, the high-energy planetary mill was employed to produce nanocrystalline ti-50al(γ)(at%) powders. initial powders were mechanically alloyed in 99.9999% and 90% purities of argon and also air atmosphere with alloying times up to 50h. the effect of impurity of argon atmosphere on the microstructure and the rate of phase transformation of ti-50al were investigated during mechanical...

Aims. This paper aims to look at the propagation of synthetic photospheric oscillations from a point source into a two-dimensional non-magnetic solar atmosphere. It takes a particular interest in the leakage of 5-min global oscillations into the atmosphere, and aims to complement efforts on the driving of chromospheric dynamics (e.g. spicules and waves) by 5-min oscillations. Methods. A model s...

Recently we have demonstrated that grass and cut grass are important sources of volatile organic compound (VOC) emissions into the atmosphere. The production of these VOCs can be traced back to plant growth, maintenance and wound defence mechanisms. The gases emitted as part of these wound defence mechanisms are responsible for the smell of freshly cut grass, and are also highly photochemically...

introduction thunderstorms pose a significant threat to modern societies and their assets. despite their local-scale characteristics, severe thunderstorms and associated extreme events like heavy rainfall, hail, gusts, or tornadoes can cause considerable damage to agriculture, buildings, or infrastructure, and facilities. thunderstorms are highly localized and largely stationary weather systems...

We present analyses of high resolution and medium resolution spectra of early L dwarfs. We used our latest set of model atmospheres to reproduce and analyze the observed features. We can model the optical flux and the atomic line profiles with the best accuracy to date. The models used to reproduce the observations