Why is bad weather usually associated with low pressure and good weather with high pressure?
In an area of low pressure, air from neighbouring areas (which are of higher pressure) moves in. It has nowhere to go but up. Upward movement of air causes condensation of water vapour, leading to the development of cloud and rain. Hence, a low pressure area usually associated with bad weather. In contrast, in an area of high pressure, the air at low levels spreads outward and air descends from aloft. Downward motion warms up the air and is favourable for evaporation. Hence, a high pressure area usually has fine and dry weather. Air descends in high pressure area and rises in low pressure area. Back to content • What is the unit of pressure? Pascal (Pa) is the international standard unit for pressure. The meteorological community uses hecto-Pascal (hPa) as the unit of pressure. It is the same as 1 millibar, a unit of pressure no longer used nowadays. Back to content • How do we compare the pressure measured at different locations? To compare pressure readings taken at different locatio
