Forecast weather with homemade Barometer...!

        Forecast weather with homemade Barometer   

           

In certain seasons in the year, the weather becomes very unpredictable. But even in that season, if you wish, you can yourself make a forecast about  the expected change in it. For this you need a barometer, the instrument that measures the air pressure. Normally in standard
barometers mercury is used. This is because it can indicate even the slightest change in the air pressure. However, for the sake of convenience we will use here coloured water only.

Materials required for this science activity are a bottle with a cork or rubber stopper, a narrow glass tube (at least 12 cm longer than the bottle), a cardboard piece and a sketch pen.

First of all, fill the bottle up to 5 cm with water and put two drops of red ink to colour it. Now make a small hole in the centre of bottle's stopper and insert the glass tube, deep enough to almost touch its bottom. Make sure that this apparatus  is airtight.

Cut out a 12 cm long strip of cardboard. Draw lines with sketch pen dividing the strip into 20 equal parts, and mark these lines. This is your scale which will have to be pasted from behind the glass tube with gum or cello-tape to measure the pressure.

First watch the tube carefully. The water level in it should be the same as in the bottle. Now put the exposed end of the tube in your mouth and blow gradually. You'll notice that when you stop blowing,
the water level in the tube rises. Blow a few more times until the water level in the tube reaches the middle of the scale. Of course it is only possible when the lid and tube are fully air tight. Well, your barometer is ready to forecast the weather for you.

If the air pressure increases, the water level in the tube will decrease and the vice versa. Now, the increase in air pressure indicates dry and pleasant weather whereas a decrease predicts rain, storm etc.

Now where to put it? The ideal place is one which is not directly affected by weather like some secure corner of your house.