When checking the weather what does the pressure tell you?

Question

When checking the weather what does the pressure tell you?

In: 503

Answer 1

Change in the atmospheric pressure leads to changing weather (cloudy vs clear). IIRC pressure drop mains rain clouds coming and pressure increase means clear(ing) skies. It can predict heavy rains and to some degree even drizzles, but it’s tricky and we use better tools for meteorology nowadays.

To be clear observing the pressure alone won’t help with prediction: it is the pressure change that actually helps, so that’s why some old school barometers need some light tapping or knocking to check which way the barometer arm swings (increase- clearing skies, decrease- incoming rain) and how much.