Weather map motion. Two-dimensional streamlines based on wind speeds at various levels show areas of convergence and divergence in the wind field, which are helpful in determining the location of features within the wind pattern. A popular type of surface weather map is the surface weather analysis, which plots isobars to depict areas of high pressure and low pressure. Cloud codes are translated into symbols and plotted on these maps along with other meteorological data that are included in synoptic reports sent by professionally trained observers. The use of weather charts in a modern sense began in the middle portion of the
Smith chart Smith chart points may be joined by straight lines to create a locus. A locus of points on a Smith chart covering a range of frequencies can be used to visually represent: The accuracy of the Smith chart is reduced for problems involving a large locus of impedances or admittances, although the scaling can be magnified for individual areas to accommodate these. A transmission line with a characteristic impedance of formula_2 may be universally considered to have a characteristic admittance of formula_3 where Any impedance, formula_5 expressed in ohms, may be normalised by dividing it by the characteristic impedance, so