GEOG 101 Lecture Notes - Lecture 30: Barometer
Document Summary
A force exerted by the weight of air above given point: the higher the reading, the greater the chance of clear weather, the lower the reading, the greater the chance of inclement weather. High pressure: descending air + sunny day//clear at night with high pressure air is sinking, thus decreasing clouds (vv) Low pressure: rising air cloudy sky//precipitation falling. Air pressure is measured using a barometer. In a mercury barometer when air pressure in high the mercury level rises. Horizontal differences in air pressure causes the wind to blow. A flow of air begins by travelling from high to low pressure. This is called the pressure gradient force (pgf) Earth is always trying to achieve a balance, thus air will try to equalize by flowing high-to-low as heat goes hot-to-cold. This wind is essentially a straight wind upon which many other forces act. In cold they compress and in warm air they get excited/expand.
