Isobars are lines of equal air pressure. The isobar lines are labeled with a number representing the air pressure in hectopascals. In high pressure systems , the air pressure increases towards the cente r. When the isobars are closely spaced, strong winds are likely to be present associated with low pressure systems. When the isobars are far apart, relative calm prevails which is usually associated with high pressure systems.
Isotherms are lines connecting points of equal temperature.
The wind direction is given by arrows. Because of the earth s rotation, the winds are deflected toward the right in the Northern Hemisphere . The coriolis effect causes the winds to blow clockwise and outward from the center of the highs, and counterclockwise and inward toward the center of the low. Weather maps also show fronts , which mark the boundary between air masses of different temperatures.