Further, the wave patterns in the upper westerlies, in very large measure, govern weather events on a variety of time scales ranging from a day to weeks, or perhaps even months. If you talk to someone else, you will get other answers. However, if the 'loops' in the pattern become locked in one geographical area, then depending where you are in relation to the upper flow, the associated surface patterns are often little changed from one day to another, and in extreme cases, from one week to another - the pattern is said to be 'blocked'. In, and just to the east of a static ridge in the flow, the surface pressure will tend to be high, with settled conditions lasting until the block is destroyed. The trough may be a slight hesitation in the upper flow, but combined with adequate moisture, and perhaps enhanced by land heating, can lead to notably more intensive shower activity, and operational forecasters are always on the look-out for such irritations at such levels as 500 hPa or 300 hPa.
Air speeds up on leaving the trough compared to entry.
Air speeds up on exit from the ridge compared to entry.