Building a barometer is a simple and fun activity, perfect for a school or home science project. You can make a rudimentary aneroid (air) barometer with a balloon, a jar and some common objects. Alternatively, you can make a water barometer with a bottle, plastic tubes, and a ruler. Both types allow you to measure atmospheric pressure, one of the values used by meteorologists to make accurate predictions.
Steps
Method 1 of 2: Build an Aneroid Barometer
Step 1. Cut the narrow part of a balloon
You can do this using a pair of scissors. It doesn't matter where you cut, as long as the opening is large enough to completely cover the jar.
Step 2. Stretch the balloon over the jar
Pull it with your hands to completely cover the opening of the jar. Make sure the balloon is stretched over the jar and has no wrinkles by pulling it down all the way around the opening.
- When the balloon is stretched over the jar, secure it by placing a rubber band around the edge of the opening.
- A glass jar is ideal for this project, but you can also use a metal can.
- Whether you decide to use a jar or a can, the exact size doesn't matter. Just make sure the opening isn't so big that you can't cover it well with the balloon.
Step 3. Glue a straw over the balloon
If the straw has a bendable part, cut it off. Apply some glue to one end of the straw and place it in the center of the balloon's surface. Most of it should hang over the rim of the jar. This straw serves to hold the indicator and allows you to record changes in atmospheric pressure.
- Silicone-based glues work very well. However, you can also use super glue, vinyl glue, or even that stick.
- Make sure the glue has dried before continuing.
- The longer the straw, the better the barometer will work (as long as it is straight). You can even insert the end of one straw into another to make a longer one.
Step 4. Attach the indicator
You can use duct tape to attach a needle to the free end of the straw so that the tip is suspended in the air. If you prefer a less pointed object, make a small arrow out of the cardboard and insert it into the hollow end of the straw. Make sure it adheres well to the plastic so it doesn't fall off. The indicator detects the up and down movements of the straw as the atmospheric pressure changes.
Step 5. Place stiff paper next to the marker
To make things easier, pin a sheet of paper to a wall and place the jar so that the pointer is facing the paper. Mark the position of the needle on the paper. Above, write "high". Below, write "low".
- A stiffer material like cardboard or cardstock will stick tighter to the wall, but you can use plain paper if you only have that. You can find everything you need in stationery or office supply stores.
- The marker should be close to the paper, but not touching the paper.
Step 6. Record the changes in the position of the indicator
When the pressure increases, the indicator will rise. When it goes down, so will the needle. Observe what happens and mark the new position of the indicator on the paper.
- If you wish, you can mark the starting needle position with "1" and then number the remaining positions in order. This is a great idea if you want to use the barometer as a science project.
- The barometer works because the air pressure pushes the balloon down, causing the indicator to rise and vice versa.
Step 7. Interpret the results
Take notes on the climatic conditions associated with changes in the position of the barometer. When the needle goes up from high pressure, is the weather cloudy or clear? When, on the other hand, is the pressure low?
Low blood pressure is usually associated with rain. High pressure can indicate a mild or colder climate
Method 2 of 2: Building a Water Barometer
Step 1. Cut the neck of a plastic bottle
Normal 1.5 liter bottles are fine. Find one empty and clean. Carefully cut the entire neck with scissors, to the point where the sides become straight and not curved.
Step 2. Put a ruler inside the bottle
It should stand upright, leaning against one side of the bottle. Tape it to the outside of the bottle. You should be able to read the numbers on the ruler.
Step 3. Insert a clear tube
It should come just above the bottom of the bottle. Tape it above the water level with tape, as the tape may weaken and peel off if it gets submerged.
- You will probably need a 40cm tube to come out of the bottle. If your tube isn't long enough, cut the sides of the bottle to make it lower.
- Leave part of the tube free.
Step 4. Dye the water your favorite color and pour it into the bottle
You only have to fill it halfway. To make the project more fun, add a few drops of food coloring to the water.
Step 5. Suck some water into the tube
Using one end of the tube like a straw, gently suck up some of the liquid. Try to bring the level to about halfway through the bottle. Since the water is colored, it should be easy to see.
- Close the free end of the tube with your tongue once you have sucked in the water, so that it doesn't go back into the bottle.
- Be careful not to suck the water all the way to the top!
Step 6. Seal the tube with something sticky
You can use sticky paste or even (used) chewing gum! Take a ball of dough without taking your tongue out of the tube. Quickly remove your tongue and immediately plug the tube with the adhesive paste. This should maintain the pressure and prevent the water from falling out.
You have to be quick in this step! If you can't, try again
Step 7. Mark the water level on the outside of the bottle
As the pressure rises, the water level drops in the bottle and rises in the tube. When the pressure drops, the water rises into the bottle and falls into the tube.
You can also mark the level changes on the ruler if you prefer, or measure how much the water level varies
Step 8. Study the data
The water in the pipe should rise when the weather is clear and drop when it rains or is cloudy. However, if you accurately record the changes in the barometer, you will notice that pressure changes occur even when the weather does not change dramatically.
Since your barometer has a ruler, you can mark pressure changes as precise changes in millimeters. Use this advantage to notice the smallest changes
Warnings
- Keep an eye on children when they use scissors and needles, as these are sharp objects.
- Balloons pose a choking hazard and should not be used by young children without adult supervision.
