GEOG 1 Lecture Notes - Lecture 16: Pressure-Gradient Force, Sea Breeze, Cool Air
Document Summary
Air always rises or falls at the dalr / salr, never at the elr. Stable air is falling air (resists vertical movement) and unstable air is rising air. To test for stability, compare moving air to the elr. If moving air is colder than elr then the air will fall and if it is warmer, air will rise. Cold air is denser than warm air : high pressure. Warm air is lighter than cold air : low pressure. Air pressure is measured using a barometer in inches of mercury or millibars. Air pressure at different locations change as surfaces heat or cool. When pressure differences exist between areas, a pressure gradient force causes air to blow from an area of high pressure toward an area of low pressure. Heavy air stays close to the earth"s surface, as it moves producing winds and forces the upward movement of warm air.
