Air pressure is caused by the weight of the air above a certain point. As air is pulled towards the Earth's surface by gravity, it becomes compressed and creates pressure.
Wind is created by differences in air pressure. Air naturally moves from areas of high pressure to areas of low pressure, creating wind as it moves.
The main factors that affect air pressure are temperature, altitude, and the movement of air masses. Changes in these factors can cause fluctuations in air pressure.
Air pressure is typically measured using a barometer, which measures the weight of the air pressing down on a certain area. The most common unit of measurement is the millibar (mb) or hectopascal (hPa).
High and low pressure systems refer to areas of the atmosphere where the air pressure is either higher or lower than the surrounding areas. High pressure systems are associated with clear, dry weather, while low pressure systems are associated with cloudy, rainy weather.