This unit will emphasize topics in meteorology and oceanography and how they relate to the various climates of the earth. We are suggesting various activities to be performed by the student throughout this unit in order to keep the student interested and motivated. We should point out at this tine that we are not striving for the student to construct perfect instruments, but they should be able to understand the basic principles of how they operate. Whenever possible, we will introduce topics to make the unit even more relevant.
All activity on earth is the result of energy from the sun. Because the earth is a sphere, not all places on earth receive the same amount of solar energy. There are other factors which also play a part in the heat exchange and we will suggest activities that can help the student understand this.
A good starting point will be for the student to get an understanding of the meaning heat and differentiate heat from temperature. We define heat as the energy in moving particles of matter measured in calories and temperature as the average kinetic energy of the particles of a substance measured in degrees.
Heat can move from one place to another by conduction, convection and radiation. One way to show conduction is to fill one cup with hot water and another filled with an equal amount of cold water. Use styrofoam cups and covers to insulate each container. Place a thermometer in each container and record the starting temperature. Connect the two containers with a metal bar and record the temperatures at set intervals.
The use of a lamp and containers containing water and a thermometer will show how bodies are heated by radiation. We can also show that the color of an object has a bearing on heat absorption. Place equal amounts of water of the same temperature in a dark container and a shiny container. Place an insulated cover with a thermometer over each and record the temperature at set intervals . The student will understand that objects can be heated by radiation and that darker colors absorb more heat than light objects.
Convection will be shown two ways. Convection in the atmosphere will be demonstrated with the use of a convection box. Using something that will give off smoke will show how the cool air falls and hot air rises. If you choose to show convection movement in a liquid, place the heat source to one side of a large beaker of water and heat. Add a drop of food coloring to the cool side of the water and observe how the food coloring sinks, moves across to the heated side and rises .
The student will now have a better understanding of heat exchange as we continue to study this unit.
As weather takes place in the layer of the atmosphere called the troposphere, we should learn about the atmosphere at this time.
The atmosphere is important to us as it filters out harmful radiation, moderates temperature, and allows life to exist as we know it. The layers of the atmosphere are divided into layers according to major changes in temperature. The main layers are the troposphere, stratosphere, mesosphere and thermosphere.
The troposphere is the layer that we live in. It consists mainly of nitrogen (78%) and oxygen(21%). Students enjoy the activity of putting steel wool in a test tube, and placing the open mouth of under water then observing the results the next day. The oxygen in the air combines with the steel wool causing the water to rise inside the test. The demonstration also leads to a good discussion on why it is good that nitrogen is plentiful in the air to dilute oxygen and lessen the effects of oxygen’s aggressive behavior.
The stratosphere is of interest to them because of the ozone layer and the jet stream. This can provide an opportunity to do extra credit work by writing a paper on the ozone layer. If you do not have a copy of the “Classroom Assessment List- Writing in Science- Middle School,” see your science representative. This document will provide the student with good organizational procedures and provide an opportunity for you to direct the student to what you are emphasizing.
Now that we know how heat travels and some characteristics of the atmosphere, we can try to understand the water cycle. Most of the earth’s surface is covered with salt water. This causes many students to wonder why rain water is not salty like ocean water. If you have the facilities to set up a distillation investigation, it will be very worthwhile. Have a saltwater mixture made up for this exercise. Have the student taste the water before and after distillation. Have them explain the two parts of the water cycle they witnessed. (evaporation and condensation) This exercise can also help the student understand how the salt content has increased over the years.
The third part of the water cycle will be understood by using the CEPUP module, “Investigating Ground water- The Fruitvale Story.” The student uses his knowledge of how ground water travels to set up a plan to test the water from various areas on the map and pinpoint the source of ground water pollution.
Evaporation, condensation and precipitation will be shown by heating water in a beaker and placing a cold object over the mouth of the beaker. The rising warm air will condense on the cool object, become heavy and fall.