How to make a rain gauge?

Experimental method:

The change of weather is closely related to the change of atmospheric pressure. Under normal circumstances, when the air pressure is stable and slowly rising, it means that the weather will clear up. On the contrary, if the air pressure continues to drop, it means that the weather will turn from sunny to rainy. We made a simple barometer ourselves, so we can predict the weather changes, so we call this instrument a rain gauge.

Take an ink bottle (other bottles are also acceptable), a 20 cm long thin glass tube, a piece of cardboard or a piece of wood, a cork (used to plug the glass bottle), a little cooking oil and two good quality rubber bands.

Use fine sandpaper to grind the fracture at both ends of the glass tube, or use a small steel chisel to smooth the fracture. In order to prevent cutting your fingers.

Drop a drop of cooking oil into the glass tube, then insert the glass tube into the cork, and then insert the cork tightly into the ink bottle.

Draw a scale of 14 cm on a piece of white paper. You can draw a scale according to the scale on a ruler or triangle (including centimeter and millimeter lines). Stick the marked white paper on cardboard or cardboard.

A rubber band is wound around both ends of a thin glass tube and then fixed on a board or cardboard card, thus making a rain gauge.

Knowledge expansion:

When the external atmospheric pressure rises, the air pressure in the bottle is less than the external atmospheric pressure, and the oil in the glass tube will move down; When the external atmospheric pressure drops, the air pressure in the bottle is greater than the external atmospheric pressure, and the oil droplets will move up. According to the position of oil droplets moving up and down, we can know the change of atmospheric pressure and judge whether the weather turns cloudy or sunny.

note:

The rain gauge should be placed in a place with stable temperature (such as basement). Otherwise, the change of temperature will affect the change of air pressure and make the observation inaccurate.

2. In order to reduce the influence of heat expansion and cold contraction of the air in the ink bottle, you can add a proper amount of water in the bottle first, so that only a small amount of air remains in the bottle.

3. The cork should be sealed with the glass tube and the ink bottle mouth, and there should be no air leakage. It can be sealed with wax or paraffin wax, or we can melt the candles we usually use for lighting and drop them where it needs to be sealed.

4. You can repeatedly observe the changes of weather and rain gauge, and make records when necessary.