Whats all the jargon associated with upper air features?
The flow in the upper Troposphere, roughly above 500 hPa / 18000 ft / 5.5km is much smoother and behaves like a vast river, not of water, but of air. As with rivers, the flow can take up a variety of patterns; from swift/straight to slow/meander and variations in-between. When it is a swift and straight flow from a largely westerly point to a largely easterly point, this is known as ZONAL flow (because the flow crosses many time/longitude zones in a short time), and if the flow is directly from west to east, this is a HIGHLY ZONAL flow. Disturbances/short wave upper troughs embedded in this flow (and the attendant surface disturbances below 500 hPa), move quickly from west to east. When the flow buckles into large amplitude meanders, the flow is said to be MERIDIONAL (because the net movement is north/south along meridians of longitude over time), and blocked situations are said to be HIGHLY MERIDIONAL: this sort of situation gives us either persistent wet weather (we are locked into t
