Air movements are what we feel as wind. Wind moves the clouds and distribute the heat and moisture across the globe. High winds are the cause of tornadoes and twisters. Observing the direction and the speed of air movements can help us to forecast weather conditions. Air has many important effects in shaping the air climate.
Why and how does the air move?
In this project you will study the cause and the direction of the air movements.
Information Gathering:
Find out about air movements. Read books, magazines or ask professionals who might know in order to find out the cause and the direction of air movements. Also find out how does the air movements affect weather conditions. Keep track of where you got your information from.
Following are samples of information that you may find.
– – AIR MOVEMENT – –
Orchids do not like stagnant air. In their natural habitat, most orchids grow high up in trees where the breezes are always blowing. Wind cools the leaves when it is hot, and helps dry excess moisture that may have accumulated on the plant. Wind also helps distribute warm and cold air so harmful air pockets don’t form.
How does a hot air balloon work? As the air inside the balloon becomes hotter than the air outside, it gets lighter. When the weight of the air inside the balloon, plus the weight of the balloon and its passengers, is less than the weight of the same volume of air outside, the balloon will begin to float in the air.
The top or side of each hot air balloon has an opening, called a vent, which can be controlled by the pilot by pulling a rope called the vent line. When the pilot opens the vent, hot air from inside the balloon is let out. Heavier cool air coming in through the bottom opening, called the mouth, replaces the escaping hot air. With more heavy air inside the balloon, it goes down.
Also review:
Question/ Purpose:
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. Following are some samples:
Question: How does the amount of heat affect the speed of air moving up above it?
Purpose: The purpose of this project (experiment 2) is to see if the speed of air (moving up) has any relation with the amount of heat used to warm up the air.
Identify Variables:
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.
The independent variable (also known as manipulated variable) is the amount of heat produced by a heat source.
The dependent variable (also known as responding variable) is the speed of air moving up above the heat source.
Constants are the air temperature.
Hypothesis:
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. This is a sample hypothesis:
More heat will create a faster air flow above the heat source. My hypothesis is based on my gathered information, indicating that hot air is lighter than cold air.
This hypothesis is being tested in experiment number 2.
Experiment Design:
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:
Introduction/ Background: Movement of the air is what we fill as wind. Wind is able to move the trees and cause ocean waves. Wind also move the clouds and change weather conditions. The purpose of this experiment is to see if the hot air moves up and if the speed of air (moving up) has any relation with the amount of heat used to warm up the air.
Procedure/ Activity: Demonstrate that hot air rises.
Click on the spiral image on the right to see the large spiral template.
Print this template on construction paper or any other heavy cardboard.
Use scissors to cut out the spiral pattern. Make sure to cut over the lines and separate the spiral from the rest of the paper.
Use a needle to make a hole in the center of the spiral where marked with a cross.
Use a sewing string to hang the spiral from its center hole or hang it over a vertical wooden stand. In either case the spiral must be able to spin freely (with no friction).
Hold the resulting spiral above a lamp that has an incandescent bulb.
What to expect? As the bulb heats up, the air above the bulb will also heat up—generating an upward-moving air current. This current will cause the spiral to rotate.
This is enough to demonstrate that the hot air rises. If you need to go further and find out if the amount if heat affects the speed of air rising up, then continue with the experiment 2.
Experiment 2:
Introduction/ Background: The purpose of this experiment is to see if the speed of air (moving up) has any relation with the amount of heat used to warm up the air. If the air moves up faster, the spiral must spin faster.
Procedure:
Prepare your setup with a lamp and a spiral hanged above it as you did in the previous experiment.
Mount a 40 watt incandescent light bulb in your lamp. Turn on the light bulb and see how the rising air will spin the spiral. Record the following information in your data table:
- The time it took for the spiral to start spinning.
- The number of turns the spiral spins in the first minute after it starts spinning.
Turn off the lamp. Wait until the bulb cools off.
Replace the bulb with a 75 watt light bulb. Turn on the light bulb and see how the rising air will spin the spiral. Record the time it took for the spiral to start spinning and the number of turns it spins in the first minute.
Repeat the above one more time with a 100 watt light bulb.
Your results table may look like this:
| Heat Source | Time to start spinning (Seconds) | Rotations in first minute |
| 40 Watt light bulb | ||
| 75 Watt light bulb | ||
| 100 Watt light bulb |
Make a graph:
Use the first and the last column of the above table to make a bar graph. Make three vertical bars; one for each of the heat sources. The height of the bar represents the number of turns the spiral spins in the first minute.
Experiment 3:
Introduction/ Background: When air or any other gas gets hot and expands, it gets less dense (lighter) because the same amount of air occupies a larger space. Hot-air balloons fly because they contain warmer, lighter air. The air in the balloon, being warm, is less dense (lighter) than the cool air around it. So it floats upward, like cork in water. When the air gets cool, the balloon will sink again.
Question: What do you think will happen when you put hot air into your balloon?
MATERIALS:
tissue paper (available in art stores and craft stores)
ruler
glue stick
pen
scissors
plastic ring or cookie cutter
string (Sewing Thread)
hair drier (have an adult help you use the hair dryer)
cardboard
- PROCEDURE:
Make a cardboard template for the balloon panels from the pattern in the right. Cut out eight leaf shaped panels from tissue paper 48″ long. 
Glue the panel edges together into a balloon shape. You could do this over an inflated rubber balloon.
Glue the right side of section 1 to the left side of section 2, and the right side of section 2 to the left side of section 3. Continue with sections 4, 5, 6, 7, and 8. End by gluing the left side of section 1 to the right side of section 8. This will make the balloon.- Cut a piece of cardboard, fold and glue into a box shape and use it as the basket.
- Make a small hole in each top corner of the box with a pencil.
- Thread one piece of thread through each of the holes you just made.
- Glue each thread on the balloon’s mouth. Allow the glue to dry thoroughly.
- Hold the top of the balloon and fill it with warm air from a hair drier set to the lowest speed. Once the air inside is really warm, let the balloon go and let it rise into the air.
DATA: Take a picture or draw a picture of your balloon. Make a data table that shows how long you held the hair drier up to the balloon and how long it stayed in the air. Vary the amount of time. Use at least three lengths of time and do at least three trials for each time. Bring your balloon to class.
CONCLUSION: You must explain what you learned by doing this activity.
Remember that you must answer the question you asked in your original problem statement.
Experiment 4:
Introduction/ Background: Hot air balloons can be made in many different shapes. Balloons have been made in the form of a cylinder, a box, animals and other objects. This is another design for a hot air balloon that you may make using tissue paper. All balloon models show that hot air is lighter and goes up.
Procedure:
Make one square that is 20 inches each side. This will form the top of the hot air balloon.
Make four rectangles that are 20″ x 26″ each. These rectangles will form the upper sides of the balloon.
Make four trapezoids that will form the lower sides of the hot air balloon.
Glue the rectangles, trapezoids and the square to form the balloon.
Make a ring from construction paper. Glue the ring to to the bottom edge of the balloon.
Hold the balloon over the hot air popper or a hair dryer. (Note: Adult supervision recommended. Be careful to avoid overheating the paper.)
Research Questions:
How high does the balloon go when it is filled with hot air for a short time or a long time.
How can you tell when it’s ready to fly?
Many things influence how well a balloon floats: the temperature and density of the air (both inside and outside the balloon), the mass of the balloon materials, and the distribution of weight.
Materials and Equipment:
List of material can be extracted from the experiment section.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Calculations:
Description
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.
Conclusion:
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.
Possible Errors:
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.
References:
List of References
- Make a hot air balloon
- Hot air balloon using a dry cleaning bag
- Air movement and natural ventilation
