Goethe's Barometer

How do we forecast the weather? Some forecast the weather when their bones are aching. But a barometer is more reliable. You can see one in the picture. It resembles a closed wine pitcher and is called Goethe barometer. If the atmospheric pressure is high, the level of liquid in the spout is low. When the pressure is low the liquid moves up.

Goethe barometer consists of two connected vessels filled with water (coloured would be best) in such a manner that there is no air flow between those two containers. The bigger container is tightly closed at the top, so that the air inside cannot escape. If the atmospheric pressure rises, the water in the spout will be forced inside, as the pressures inside have to be balanced, and the level of water in the spout will drop. In the other container, the change is imperceptible as the diameter of the container is much bigger. In contrast, when the atmospheric pressure is low, the level of liquid rises.

Unfortunately, this barometer is not particularly precise and the air presence in the bigger container is the main culprit.