1) What is air pressure? (Answer: Atmospheric pressure, sometimes also called barometric pressure, is the pressure within the atmosphere of Earth.)
2) What is a barometer and what is it used to measure? (Answer: A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather.)
3) How does air pressure change? (Answer: Millibar values used in meteorology range from about 100 to 1050. At sea level, standard air pressure in millibars is 1013.2. Weather maps showing the pressure at the surface are drawn using millibars. ... This change in pressure is caused by changes in air density, and air density is related to temperature.)
4) Why is cooler, drier air related to High Pressure? (Answer: This is due to density differences between the two air masses. Since stronger high-pressure systems contain cooler or drier air, the air mass is denser and flows towards areas that are warm or moist, which are in the vicinity of low pressure areas in advance of their associated cold fronts.)
5) Why is warm, moister air related to Low Pressure? (Answer: When air warms, its molecules scatter. The air becomes lighter and rises.)