Barometer Simultaneous barometric readings from across a network of weather stations allow maps of air pressure to be produced, which were the first form of the modern weather map when created in the 19th century. Isobars, lines of equal pressure, when drawn on such a map, give a contour map showing areas of high and low pressure. Localized high atmospheric pressure acts as a barrier to approaching weather systems, diverting their course. Atmospheric lift caused by low-level wind convergence into the surface brings clouds and sometimes precipitation. The larger the change in pressure, especially if more than 3.5 hPa (0.1 inHg),
Desorption atmospheric pressure photoionization is normally used in the presence of a matrix, such as matrix assisted laser desorption ionization (MALDI), but research has combined techniques of laser desoprtion in atmospheric pressure conditions to produce a method that does not use a matrix or discharge. This method is able to help with smaller compounds, and generates both positive and negative ions for detection. A transmission geometry is taken as the beam and spray are guided at a formula_3angle into the coupled MS. Studies have shown the detection of organic compounds such as: farnesene, squalene, tetradecahydro anthracene, 5-alpha cholestane, perylene, benzo perylene, coronene, tetra decylprene,