Contour line future weather patterns. Isobars are commonly used in television weather reporting. Isallobars are lines joining points of equal pressure change during a specific time interval. These can be divided into "anallobars", lines joining points of equal pressure increase during a specific time interval, and "katallobars", lines joining points of equal pressure decrease. In general, weather systems move along an axis joining high and low isallobaric centers. Isallobaric gradients are important components of the wind as they increase or decrease the geostrophic wind. An isopycnal is a line of constant density. An "isoheight" or "isohypse" is a line of constant geopotential
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