Contour line factors in a weather system. An isobar (from or "baros", meaning 'weight') is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure. More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time. In meteorology, the barometric pressures shown are reduced to sea level, not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict
Atmospheric-pressure laser ionization atmospheric pressure (AP) ion source with APLI. In principle only the ionizing laser light has to be coupled into the existing ion source through UV transparent windows. Couplings with separation methods like Supercritical Fluid Chromatography (SFC) and Chip-Electrospray (Chip-ESI) have also been demonstrated with APLI. APLI is a selective ionization method, because the 1+1 REMPI ionization requires an adequate existing electronic intermediate state and both electronic transitions must be quantum mechanically allowed. UV tunability and discrete energy states of analyte allow improved ionization with reduced background signal. In particular polynuclear aromatic compounds fulfil the spectroscopic requirements for 1+1 REMPI, thus