Pressure Patterns Pressure Patterns Pressure varies all over the world. Centres of low pressure, called lows or depressions, bring cloudy, wet and sometimes windy weather. Centres of high pressure, called highs or anticyclones, bring settled, dry and often sunny weather. The way highs and lows move from day to day causes changes in the weather.
Pressure is measured at different places on the Earth using a barometer.
This information is then used to draw an isobar chart. An isobar chart like the one shown above shows lines of equal pressure and also indicates where the pressure is low and high. Study the map carefully and decide what the pressure will be at X . Different lattitudes of the Earth are heated at different rates creating areas that are warmer or cooler than others. In warm areas the air is heated and rises causing a drop in pressure.