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 chemical ionization ionized, which produce N. The evaporated mobile phase of LC acts as the ionization gas and reactant ions. If water is the only solvent in the evaporated mobile phase, the excited nitrogen molecular ions N would react with HO molecules to produce water cluster ions H(HO). Then, analyte molecules M are protonated by the water cluster ions. Finally, the ionization products MH(HO) transfer out from the atmospheric-pressure ion source. Declustering (removal of water molecules from the protonated analyte molecule) of MH(HO) takes place at the high vacuum of the mass analyzer. The analyte molecule ions detected by MS are [M+H].