Surface weather analysis United States, temperature and dewpoint are plotted in degrees Celsius. The wind barb points in the direction from which the wind is coming. Each full flag on the wind barb represents of wind, each half flag represents . When winds reach , a filled in triangle is used for each of wind. In the United States, rainfall plotted in the corner of the station model are in inches. The international standard rainfall measurement unit is the millimeter. Once a map has a field of station models plotted, the analyzing isobars (lines of equal pressure), isallobars (lines of equal pressure change),
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