Clouds rain and strong winds often occur in these regions. See high pressure system , low pressure system , cold fronts and parcels of air for more detailed and information. This shows a typical pattern of high and low pressure regions. The curved blue lines are called isobars . These pass through areas with the same air pressure.
Air pressure is measured in hectopascals.
On this weather map the isobars are at 4 hectopascal intervals. The black arrows show the wind direction. High and low pressure regions do not stay in the same place. They move over the Earth's surface. The purple line with barbs is a cold front .