Introduction: (Initial Observation)
Wind speed is one of the important values that we use to predict the weather conditions. Wind speed is a factor in designing buildings and bridges. Such structures must be resistant to the force of the wind. With recent interests in renewable energy and use of wind turbines, it is important to know the wind speed in different heights. Meteorologists use wind speed to predict the movements of clouds, cold air and warm air.
Wind speed also affects the travel time of aircrafts. If they are traveling in the wind direction, they move faster. If they are traveling against the wind direction, they move slower. If the wind speed and direction vary in different elevations, pilots may be able to choose the best elevation for their flight.
Since the speed and direction of the wind can have so many important affects in our lives, this is the project of my choice.
Find out about what you want to investigate. Read books, magazines or ask professionals who might know in order to learn about the effect or area of study. Keep track of where you got your information from.
Click HERE to see the current wind speed in different US regions.
You can visit windpower.org to calculate the wind speed at different elevations. They have a program that can also plot the changes of wind speed in relation to the elevation.
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to find out if the wind speed and direction varies in different heights.
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Independent variable (also known as manipulated variable) is the height.
Dependent variables (also known as responding variables) are the wind speed and the wind direction.
Controlled variables are test methods, test location and test time.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. Following is a sample hypothesis:
I think the ground and objects such as buildings and trees slow down the wind speed at ground level. So the speed of wind increases by height; however, the wind speed may reduce or the direction may change after certain heights.
My hypothesis is based on my observation of wind current images in books.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment 1: Making An Anemometer
In this experiment you will make a simple anemometer.
Introduction: An anemometer is a device that tells you how fast the wind is blowing. The device you can build is a model of a wind speed indicator. A real one will be able to accurately measure how fast the wind is blowing. Yours will give you only approximation of how fast it’s blowing. It can’t give you an exact wind speed.
In a more advance anemometer, the energy in the moving wind can be used to generate electricity. Based on the amount of electricity, you may determine the actual wind speed.
- Cut off the rolled edges of the paper cups to make them lighter.
- Color the outside of one cup with the marking pen.
- Cross the cardboard strips so they make a plus (+) sign. Staple them together. (You may use balsa wood instead of cardboard strips. Balsa wood is light, strong and is available at craft stores)
- Take the ruler and pencil and draw lines from the outside corners of where the cardboard strips come together to the opposite corners. Where the pencil lines cross will be the exact middle of the cross.
- Staple the cups to the ends of the cardboard strips; make sure the cups all face the same direction.
- Push the pin through the center of the cardboard (where the pencil lines cross) and attach the cardboard cross with the cups on it to the eraser point of the pencil. Blow on the cups to make sure the cardboard spins around freely on the pin.
- Place the modeling clay on a surface outside, such as a a porch railing, wooden fence rail, a wall or a rock. Stick the sharpened end of the pencil into the clay so it stands up straight.
Your anemometer is now ready for use!
Experiment 2: Improve your Anemometer
Try to come up with better ideas in your anemometer design. Anemometer works based on a simple principle that some objects such as a cup or a cone, have more resistance to the air current from one side than the other. such a difference makes the anemometer work. Anemometer wheel should be able to spin freely. It should spin with any slow or fast wind.
Some of the ideas in improving your anemometer are:
- Use wood dowel instead of pencil and make a wooden stand for it.
- Use cones instead of cups. Make cones using construction paper.
- Mount a spool on the base and let the thread wrap around the dowel when the anemometer spins. In this way you can use the length of thread around the wood dowel to determine how fast did the anemometer wheel spin. (How many turns per minute)
Picture in the right shows an anemometer mounted on a small electric generator. The idea is that the amount of electricity (voltage) produced by the small generator has a direct relation to the wind speed. If this works, you may measure know the wind speed by knowing the produced voltage.
To know the relation between the wind speed and the voltage, student decided to test the anemometer in a moving car. He hold the anemometer out of the window, while his father drove in a safe area with 3 different speeds of 10mph, 20mph and 30mph.
Points observed during this test are:
- Electric generator creates some resistance, so the anemometer wheel can not spin freely.
- Cups do not provide enough power for the generator to spin fast. Cones provide a better result.
- Increasing the diameter of the anemometer wheel makes the anemometer spin easier while it is connected to a generator. (Cardboard strips or balsa wood strips must be longer)
Can you cut a plastic ball in half and use it instead of the cone to make an anemometer?
How about using plastic spoons to make a different design of anemometer?
Experiment 3: Other methods of measuring wind speed
movements of a flag or an object that is hanging from some point can also be used to estimate the wind speed. In this experiment you will use a protractor, 12″ fishing line or cotton thread and a ping-pong ball to make a device for measuring wind speed.
- Tape the straight edge of the protractor to the top of the ruler so that the curved edge of the protractor is hanging below the ruler.
- Tape one end of a 12″ piece of fishing line to a ping-pong ball.
- Tape the other end to the middle of the straight section of a plastic protractor.
- Hold the ruler parallel to the ground pointing it in the direction the wind is coming from.
- The ping-pong ball will blow out at a particular angle with the fishing line over a specific number on the protractor.
- Use the chart below to find the wind speed that corresponds to the number or angle of the fishing line and the protractor.
Degrees on Protractor
Wind speed in mph
Experiment 4: Compare wind speed at different heights.
The movements of flags is affected by the wind speed. In this experiment you will use a tall flagpole to compare the speed at different altitudes.
Find a tall flag pole in an open area. Bring down and temporarily remove the flag. (Get necessary authorization)
Cut ribbons in 3 feet long pieces.
Using a knot and a piece of masking tape connect one ribbon to the rope.
Pull it up 3 feet.
Connect another ribbon and pull it up again another three feet. Repeat this until the first ribbon is all the way on the top of the pole.
Observe the movements of the ribbons, their expansion, their angle with the pole and their direction. Each ribbon shows the status of the wind speed and direction in a different altitude.
Record your observations. Take pictures if possible. It is easier to make observation and analysis using pictures. In your analysis you decide if the wind speed and direction varies in different altitudes in the range that you have tested. In other word if your limited range test does not show a change in wind speed or direction, it does not mean that it does not also change in higher altitudes.
The above diagram is a fictional drawing of different result possibilities for this experiment.
Experiment 5: Observe wind direction in different heights.
A helium balloon moves easily by wind currents. Helium balloons are frequently used to study weather conditions. You can use helium balloons to determine changes in wind direction in different elevations.
Release 5 freshly filled helium balloons in 5 second intervals. Balloons will go up, but at the same time they move to the direction of the wind.
Observe all five balloons movements in relation to your location or release point.
After releasing the fifth balloon, you have five balloons at five different altitudes. Are all of them moving in the same direction?
Record your observation and use them for your analysis and drawing conclusion.
Can you tell if the direction of wind varies in different altitudes by looking at clouds in different altitudes?
Materials and Equipment:
The list of material depends on your final experiment design. You may extract a list of material from the experiment procedures. You may also have to change or substitute some material. Following is a sample list of material for experiment 1.
What You’ll Need for Experiment 1:
- 4 small paper cups (like drinking cups)
- A marking pen (any color)
- 2 strips of stiff, corrugated cardboard — the same length
- Push pin
- Sharpened pencil with eraser on the end
- Modeling clay
- A watch that shows seconds
Results of Experiment (Observation):
Measuring Wind Speed
This anemometer cannot not tell the wind speed in miles per hour, but it can give you an idea of how fast the wind is blowing.
Using your watch, count the number of times the colored cup spins around in one minute. You are measuring the wind speed in revolutions (turns) per minute. Weather forecasters’ anemometers convert the revolutions per minute into miles per hour (or kilometers per hour). Keep a record of the wind speeds you’re measuring for the next few days.
Measure the wind speed at different times of the day. Is it the same in the morning; the afternoon; the evening? Move your anemometer to another location. Is it windier in other places? Do trees or buildings block the wind?
No calculation is required.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.