Cold Air Advection (CAA) is the movement of colder air on a constant height surface toward a location. Two influences on the rate of CAA include how quickly the temperature changes over distance and how quickly the air from a colder location is moving toward a warmer location. Thus, the rate of CAA depends on the thermal gradient and the component of wind speed that is moving the colder air in. The importance of cold air advection is that it tends to bring in colder air, more stable air, and drier air. CAA occurs behind cold fronts and can occur when air flows from higher latitude toward lower latitudes. The image below shows Cold Air Advection occurring over much of the eastern U.S.. Temperature decreases with the colors going north. The winds are from the north. The northerly winds are helping to push the temperature isotherms toward the south. This will cause a decrease in temperature over time. There are two examples on the image where little to no CAA is occurring. One location to focus on is the region over the eastern Great Lakes. The temperature does not change much over distance thus CAA can’t occur there. Another focus area is over Missouri. The wind is weak and CAA can’t occur without wind.  |