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Make a homemade barometer science experiment – how to make a real working barometer from a soda bottle.

Closeup face of a barometer

Make a homemade barometer science experiment

The air pressure around us affects our weather. Notice how your weatherman always mentions various pressure systems (low-pressure system, high-pressure system, etc.) and how they will affect tomorrow’s weather. In this experiment, we will create a tool that lets you gauge the pressure of the air around you.

  1. Fill the measuring cup or glass with water and add some colored dye to it.
  2. Flip the empty soda bottle upside down into the glass measuring cup.
  3. Make sure that you use a bottle that is just the right size. The thicker body of the bottle should fit snugly in the measuring cup so that the mouth of the bottle does not touch the bottom of the cup.
  4. Make sure that the level of the water extends into the neck of the bottle.
  5. Mark a line on the cup to indicate the water level within the bottle.
  6. Reexamine the bottle in a few days.

Notice the change in the water level?  The amount of air within the bottle is fixed and cannot change since the water extended into the bottle acts as a ‘plug.’  Hence, you can consider the amount of air trapped in the bottle as an indicator of the air pressure on the day you plugged the bottle.  The pressure on the water’s surface depends on the current air pressure.  When the air pressure increases (as it does in drier weather), the pressure on the surface of the water is greater, and the water is forced into the bottle, changing the water level.  If you see the water level drop, find your umbrella…

How air pressure determines the weather

Air pressure is the weight of the Earth’s atmosphere pressing down on its surface. Air pressure is an important factor in determining the weather. It is affected by temperature, altitude, and humidity.

When air pressure is high, it means that the air is dense and heavy. This usually results in fair weather, with clear skies and little precipitation. High pressure systems can also cause temperature inversions, where cool air is trapped near the ground and warmer air is above.

On the other hand, when air pressure is low, it means that the air is less dense and lighter. Low pressure systems usually result in cloudy, stormy weather, with high chances of precipitation. Low pressure systems can also cause strong winds and hurricanes.

Fronts are the boundaries between high- and low-pressure systems. When a cold front (low pressure) meets a warm front (high pressure), it can cause thunderstorms, tornadoes, and other severe weather events.

How a barometer works

A barometer works by measuring the atmospheric pressure and converting it into a height of liquid in a glass tube. It is an essential tool in weather forecasting and aviation and helps us to understand and predict changes in the weather. It was first invented in the 17th century and has since been used widely in weather forecasting and aviation.

A typical barometer consists of a glass tube that is sealed at one end and open at the other. The tube is filled with mercury or sometimes water, and then turned upside down so that the open end is submerged in a cup of mercury or water. The pressure of the atmosphere on the surface of the mercury or water in the cup forces the liquid up the tube, creating a vacuum in the space above the column. The height of the column is directly proportional to the pressure of the atmosphere.

There are two types of barometers: mercury and aneroid. Mercury barometers are more accurate and are commonly used in weather stations, while aneroid barometers are smaller, portable, and used for personal use.

Supplies required for the homemade barometer science experiment

Supplies: Plastic bottle, Food dye, Glass jar

Image Credits

In-Article Image Credits

Hersteller Lion & Guichard Frankreich barometer thermometer and wind speed instrument (1870) via Wikimedia Commons with usage type - Creative Commons License. August 20, 2020
Closeup face of a barometer via Wikimedia Commons by James Petts with usage type - Creative Commons License. March 10, 2012
Table of Pneumaticks, from the 1728 Cyclopaedia, Volume 2 via Wikimedia Commons with usage type - Public Domain. 1728

Featured Image Credit

Closeup face of a barometer via Wikimedia Commons by James Petts with usage type - Creative Commons License. March 10, 2012


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