A barometer measures the rising and lowering of pressure of the atmosphere. High pressure indicates clear weather; low pressure indicates less favorable weather.
- A clear bottle with a neck (catsup or vinegar bottles work well)
- A clear, narrow glass jar (to hold about 2 cups or 480 ml of water)
- Food coloring
- Permanent marker
- Remove all labels from the jar and bottle.
- Clean thoroughly. Invert the bottle into the jar, making sure the bottle does not touch the bottom of the jar.
- Fill the jar with enough water to reach just over the mouth of the Inverted bottle by an inch (2.5 cm) or so.
- Add a few drops of food coloring to the water.
- Release air bubbles from the bottle by tipping it gently.
- Using a permanent marker, mark the water level on the jar. Place the barometer in a shaded area.
- Throughout the week, observe the level of the colored water.
- The water level in the bottle should be high during good weather and low in bad weather.