Barometer measures air pressure and this is expressed in millibars (mb)/hectoPascal(hPa).
If the pressure falls or rise quickly, it means that change is fast approaching; the isobars are tightening, therefore the wind is increasing. The faster the change, usually, the worse the conditions.
The standard pressure at sea level is approximately 1013hPA and changes in pressure have an effect on sea level height.
High pressure pushes down on the sea reducing it’s height.
Low pressure allows the sea level to rise.
Example: A Change of 10 millibars changes the height by 0.1 of a meter. therefore if we have a high pressure of 1040 it would reduce the height by nearly 0.3m. A low pressure of 960, there may be 0.5m more water.
Important: Pressure combined with wind, can have some serious affects on the level of sea we expect.
Anemometers: Measures wind speed and direction.