Students will learn about the barometer and how it helps to predict the weather.
The Highs and Lows of Weather
The Discovery of the Barometer
As previously mentioned, Earth's air has pressure because of the air molecules stacked on top of each other from Earth's surface to the edge of space which is about 70 vertical miles. This pressure is greatest at Earth's surface, and gradually this pressure lessens as the air goes vertical toward space. However, as previously mentioned, the air pressure can change at and near Earth's surface. It changes because of more pressure put on these air molecules or less pressure on these air molecules. It is this pressure change at and near Earth's surface that brings us our different weather. It has an effect on the temperature, the movement of the air (wind), the types of clouds that will form, and the type of precipitation. And most of all, the changing air pressure is what makes the water cycle continue to go on and on and on.
There is an instrument that we use to measure the air pressure and it is called a barometer. There are numbers on a barometer that range from 28 to 31. One misconception that many people have about the barometer is that a barometer measures temperature because of these numbers. But these numbers measure the air pressure. (The story in Activity One will tell you why we use these numbers.) Another misconception about the barometer is that people believe that the barometer tells us what the weather is right now. The most fascinating thing about the barometer is that the barometer tells us what that weather is going to be in one or two days. It is a device for predicting the weather.
Generally, if the needle on a barometer is above 30, our area is going to have nice weather for at least one to two days. The higher the needle is above 30 the nicer the weather will be. Generally, if the needle of a barometer drops below 30 there is going to be change in the weather. The temperature is going to change, clouds will be moving in, there is going to be a change in the air movement (wind), and we could get some precipitation. The lower the needle moves below 30, the more drastic these changes will be in a couple of days. Generally, if the barometer is at 30 this means we could lose our very nice fair weather to some wind, partly clouded skies, and a slight temperature change, but usually with no storms on the horizon. The 30 means that a storm is nearby, but it isn't going to reach us.
1- Use Science Process and Thinking Skills
3- Understand Science Concepts and Principles
Invitation to Learn
The Highs and Lows of Weather
Pass out to the students a weather map from the newspaper that has many highs (H) and lows (L) on it. They can each have his/her own copy of different days or make a copy so each student gets the same one.
The Discovery of the Barometer (a teacher demonstration)
The Story of the First Barometer
Around the time of 1643, there was a young scientist/mathematician by the name of Evangelisti Torricelli who was very interested in air pressure. (Put on the picture of Torricelli.) Scientists at the time knew that air pressure existed and they knew that it changed. They had an idea that when there was an air pressure change there was going to be stormy weather. But, they had no way of measuring the air pressure like they could measure temperature with a thermometer. Torricelli was very interested in finding a way to measure air pressure so he could see air pressure changes.
One day Torricelli got a three-foot glass tube that was closed in at one end and open at the other. (Show the picture of Torricelli with the tube in his hand.) With a suggestion from his friend, Galileo, he filled the glass tube with mercury. (Show the plastic tube.) Mercury is a liquid metal that is much heavier than water. He also had a bowl of liquid mercury. (Show the bowl of colored water.) After filling the glass tube with mercury, he tipped the tube upside down, holding the open end with his finger so the mercury wouldn't run out. (Demonstrate this with the plastic tube.) With his finger on the end he gently put the open end of the tube in the bowl of mercury. He then took his finger off the glass tube. (Put the tube into the water and take your finger off.) At his surprise the mercury dropped about 6 inches to the 30-inch mark. (Point to the 30-inch mark on the tube.) He marked this point as a reference point so he could notice any changes in the level of the mercury inside the tube.
He set his mercury instrument up in a safe place in his laboratory and observed it many times a day. He put marking on the tube so he could see if the mercury level moved inside the tube. (Put on the picture of the two mercury tubes showing the two dates of the low and high mercury markings.) On October eighth he noticed that the mercury dropped below the 30-inch mark. (Point to the mark below the 30-inch mark on the plastic tube.) Then a day later he observed that weather had changed and became stormy. On October eleventh he noticed that the mercury jumped above 30-inch mark. (Point to the mark above the 30-inch mark on the plastic tube.) He observed that the weather was fair a day or two later. (Show the picture of the arrows pressing on the bowl of mercury.) He kept track of the changes of the level of the mercury in the tube.
Torricelli concluded that whenever the level of the mercury was below the 30-inch mark a storm was coming. And, the farther the mercury level was below the 30-inch mark the worse the storm. This is why we use the word "Low" because the mercury was lower than 30 inches in the tube. (Refer they weather map they looked at in the Invitation to Learn.) He also concluded that whenever the level of the mercury was above the 30-inch mark, fair weather was in its way. And, the farther the mercury level was above the 30-inch mark the better the weather was going to be. This is why we use the word "High" because the mercury was higher than 30 inches in the tube. (Refer they weather map they looked at in the Invitation to Learn.) (Show the picture of a mercury barometer today.) Meteorologists still use the mercury barometer today, because it is the most accurate instrument to use to measure air pressure change.
Neufeld, P., (2006). Comprehension instruction in content area classes. Reading Teacher, Vol. 59 (Number 4), Page 302
For students to be able to successfully comprehend the texts of social studies and science, teachers need to be teaching comprehension strategies and not leave them alone in finding their own devises. Ideas to consider in comprehension in content reading are:
Fisher, D., Ivey, G., (2005). Literacy and language as learning in content-area classes: a departure from "every teacher a teacher of reading". Action in Teacher Education, Vol. 27 (Number 2), Page 2
All learning is language based. Including reading and writing regularly as ways for students to gain new information is important. Before, during, and after a prescribed activity, reading, writing, listening, viewing, and discussion should play a larger role than lecture. In the content areas creating the reading and writing experiences should focus on the big ideas.