Translations:Adventist Youth Honors Answer Book/Nature/Weather - Advanced/53/en
From Pathfinder Wiki
An isobaric analysis involves the construction of lines of equal mean sea level pressure on a geographic map. The innermost closed lines indicate the positions of relative maxima and minima in the pressure field. The minima are called low pressure areas while the maxima are called high pressure areas. Highs are often shown as H's whereas lows are often shown as L's. Elongated areas of low pressure, or troughs, are sometimes plotted as thick, brown dashed lines down the trough axis.