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 selectivity of APLI is one factor contributing to the selectivity, but under LC conditions, APPI suffers from another effect: The VUV light utilized by APPI does not penetrate deep into the ion source geometry, because the solvents used by LC, which are present as vapor in the ion source, strongly absorb the VUV light. For the UV light of APLI the LC solvents are virtually transparent, thus APLI allows the generation of ions in the entire ion source volume. In contrast to other ionization methods such as electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI), APLI allows the generation of