At high altitudes there is less atmospheric pressure , making it more difficult for the lungs to extract oxygen from the air.在高海拔处气压低，肺部从空气中吸氧困难。We use atmospheric pressure readings from barometers to forecast the weather.我们利用气压计上的气压读数来预报天气。A barometer is sensitive to changes in atmospheric pressure.气压计对气压的变化反应很灵敏。The cylinder swelled and contracted with the changing atmospheric pressure.随着大气压力的变化，圆筒会膨胀和收缩。