Surface weather analysis isotherms (lines of equal temperature), and isotachs (lines of equal wind speed) are drawn. The abstract weather symbols were devised to take up the least room possible on weather maps. A synoptic scale feature is one whose dimensions are large in scale, more than several hundred kilometers in length. Migratory pressure systems and frontal zones exist on this scale. Centers of surface high- and low-pressure areas that are found within closed isobars on a surface weather analysis are the absolute maxima and minima in the pressure field, and can tell a user in a glance what the general weather is
Area chart use vertical and horizontal lines to connect the data points in a series forming a step-like progression are called "step-area charts". Area charts in which data points are connected by smooth curves instead of straight lines are called "spline-area charts". Area chart An area chart or area graph displays graphically quantitative data. It is based on the line chart. The area between axis and line are commonly emphasized with colors, textures and hatchings. Commonly one compares two or more quantities with an area chart. William Playfair is usually credited with inventing the area charts as well as the line, bar,