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
Closest pair of points problem left of the dividing line we have to compare the distances to the points that lie in the rectangle of dimensions bordering the dividing line on the right side, as shown in the figure. And what is more, this rectangle can contain at most six points with pairwise distances at least . Therefore, it is sufficient to compute at most left-right distances in step 4. The recurrence relation for the number of steps can be written as , which we can solve using the master theorem for divide-and-conquer recurrences to get . As the closest pair of points define an