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
Group of rational points on the unit circle is just "a"/"c" + "ib"/"c", where "i" is the imaginary unit. Conversely, if ("x", "y") is a rational point on the unit circle in the 1st quadrant of the coordinate system (i.e. "x" > 0, "y" > 0), then there exists a primitive right triangle with sides "xc", "yc", "c", with "c" being the least common multiple of "x" and "y" denominators. There is a correspondence between points ("x","y") in the "x"-"y" plane and points "x" + "iy" in the complex plane which will be used below, with ("a", "b") taken as equal to "a" + "ib". The set of