27 research outputs found
A collection of sub-daily pressure and temperature observations for the early instrumental period with a focus on the \u27year without a summer\u27 1816
The eruption of Mount Tambora (Indonesia) in April 1815 is the largest documented volcanic eruption in history. It is associated with a large global cooling during the following year, felt particularly in parts of Europe and North America, where the year 1816 became known as the “year without a summer”. This paper describes an effort made to collect surface meteorological observations from the early instrumental period, with a focus on the years of and immediately following the eruption (1815–1817). Although the collection aimed in particular at pressure observations, correspondent temperature observations were also recovered. Some of the series had already been described in the literature, but a large part of the data, recently digitised from original weather diaries and contemporary magazines and newspapers, is presented here for the first time. The collection puts together more than 50 sub-daily series from land observatories in Europe and North America and from ships in the tropics. The pressure observations have been corrected for temperature and gravity and reduced to mean sea level. Moreover, an additional statistical correction was applied to take into account common error sources in mercury barometers. To assess the reliability of the corrected data set, the variance in the pressure observations is compared with modern climatologies, and single observations are used for synoptic analyses of three case studies in Europe. All raw observations will be made available to the scientific community in the International Surface Pressure Databank
Silver nanoparticles grafted onto PET: Effect of preparation method on antibacterial activity
Ballistic Evaporation and Solvation of Helium Atoms at the Surfaces of Protic and Hydrocarbon Liquids
Atomic
and molecular solutes evaporate and dissolve by traversing
an atomically thin boundary separating liquid and gas. Most solutes
spend only short times in this interfacial region, making them difficult
to observe. Experiments that monitor the velocities of evaporating
species, however, can capture their final interactions with surface
solvent molecules. We find that polarizable gases such as N<sub>2</sub> and Ar evaporate from protic and hydrocarbon liquids with Maxwell–Boltzmann
speed distributions. Surprisingly, the weakly interacting helium atom
emerges from these liquids at high kinetic energies, exceeding the
expected energy of evaporation from salty water by 70%. This super-Maxwellian
evaporation implies in reverse that He atoms preferentially dissolve
when they strike the surface at high energies, as if ballistically
penetrating into the solvent. The evaporation energies increase with
solvent surface tension, suggesting that He atoms require extra kinetic
energy to navigate increasingly tortuous paths between surface molecules