1. HYGROMETER Brandon Hunter, Class 707
Science Fair Presentation (May 2009)
Ms. Allen

2. Weather Elements
Humidity, Temperature, Atmospheric Pressure, Humidity, Clouds, and Precipitation.

3. Weather Montage Project Explanation
The montage on the previous slide was made to show the six elements of weather. They are temperature, wind, pressure, humidity, clouds, and precipitation.
Temperature is the measure of how hot or cold something is. It’s measured on a type of scale that has one or more fixed reference points, otherwise known as a thermometer.
Wind is a current of air that moves across the Earth’s surface.
Pressure is the amount of matter or weight on something.
Humidity is the amount of water vapor in the atmosphere. It is usually expressed as “relative humidity”.
Clouds are visible bodies of fine water droplets or ice particles in the atmosphere. The altitudes of clouds range about several miles above sea level.
Precipitation is any form of water – such as rain, snow, sleet, or hail – that falls to the Earth’s surface.

4. Purpose
The purpose of the following experiment is to make a HAIR HYGROMETER to measure the humidity in the air.

5. History
A hygrometer is an instrument that measures the humidity in the atmosphere, air, or any gas. The first ever hygrometer was created in the 1400s by Leonardo DaVinci. With his hygrometer, he wanted to determine the imbalance caused by the absorption of the moisture by a piece of cotton, which was equal to the weight on the other side of the scale. Leonardo spent most of his time studying the atmosphere both as a scientist and an artist. He would record most of his observations in the drawings he produced.

6. Introduction Last year, I attempted to build a hair hygrometer.
Unfortunately, when I conducted this experiment, I encountered some difficulties.
The quality of the hair that was required for the project wasn’t the right texture.
Due to this, I didn’t get the readings I needed.

7. Hair Hygrometer Materials
Piece of hair at least 9 inches long
Half-gallon cardboard milk carton
Scissors
Darning needle
Broom straw
Glue
Paper clip
Tape
Penny
Plain index card

8. Procedure Wash the hair clean with soap and water.
Under adult supervision, cut a small “H” in the side of the milk carton, about one-half the length of the darning needle.
Bend back the tabs and push through.
Poke a broom straw into the eye of the needle and glue in place.
At the end of the carton, cut a small slit and push the paper clip through it. Glue it in place.
Tape one end of the hair to the paper clip.
Lay the hair over the needle and loop it around the needle once. Then let it hang over the end of the box opposite the paper clip.
Tape the penny to the free end of the hair.
Draw a half-circle on the index card and divide the half-circle with 10 marks. Label the marks 1 through 10 beginning on the left side.
Glue te index card to the box under the broom straw.
Take your completed hygrometer into the bathroom and run the water in the show until the mirror fogs up. The air will be 100% humid and will cause the hair to stretch.
Adjust the straw so that it points to 10.
Put the hygrometer outdoors in a sheltered place such as under a porch.
Tap it gently a few times before taking a reading to make sure the straw isn’t stuck in place.

9. Can a hygrometer measure the moisture in the air?
Problem
What makes people hot and sweaty? Is it the heat or the humidity in the air?
Can a hygrometer measure the moisture in the air?

10. Hypothesis
I hypothesize that if I put the hygrometer in the humid bathroom, the hair will get really moist because of the humidity. Due to the moisture, the hair will have enough weight to pull the penny down, causing the broom straw to move and give a reading towards the “Wet” markings on the index card. Consequently, when I put the hygrometer outdoors, the broom straw will move back towards the “Dry” markings because the air won’t be so wet and thick.

11. Data/ Analysis

12. Conclusion
My hair hygrometer failed again. Even though I used a different type of hair this time (natural, unrelaxed hair), instead of the type of hair that I used last year (chemically straightened, otherwise known as “relaxed”), the hygrometer didn’t work. Once again, the hair didn’t stretch when the hygrometer was placed in the humidity. In addition, when I did the experiment a sixth time, the broom straw didn’t move at all. I also expected the broom straw to give me high readings all of the time. However, every day that I did the experiment, my results got lower, then rose again.

16. Bibliography
* From Class Notes (3/22/09)