Snow Flakes

Introduction: (Initial Observation)

Snow is an important source of drinking water as well as water for farming and agricultural use. Unlike rain, snow stays solid for many months in the elevations and melts gradually so the continuous running water will remain available for many months. Because of the importance of snow, many scientists and organizations continuously watch, test, analyze and report the condition of snow falls in different areas. While snow is very important for our lives, many are attracted by the amazing shapes of snow flakes. The cause of so many interesting shapes has always been a question.

In this investigation we attempt to find answers to:

1. 1. How can we test the snow and why? (experiment 3)
   2. How can we watch the structure of snow flakes using a magnifier or microscope? (Experiment 4)
   3. What factors affect the shape of snow flakes. (experiment 2)

Adult supervision and help is required for the experiments.

Information Gathering:

Find out about snow and how it forms. Read books, magazines or ask professionals who might know about the factors that may affect the shape of snow crystals. Keep track of where you got your information from. Following links and information can help you to start.

http://www.macatawa.org/~oias/snowflak.htm

http://www.msnbc.com/news/362013.asp

http://www.its.caltech.edu/~atomic/snowcrystals/photos/photos.htm

http://www.its.caltech.edu/~atomic/snowcrystals/class/class.htm

Studying Snowflakes

Get a cardboard box to store your equipment in and place everything in a sheltered spot at outdoor temperatures. An unheated garden shed or garage works well. Having all your equipment cold will keep the snowflakes from melting too fast while you look at them. In the box, put some black construction paper, a soft paintbrush, some toothpicks, and a magnifying glass. If you would like to try to preserve snowflakes, add a can of hair spray or artist’s fixative and some glass microscope slides. If you want to try to preserve snowflakes, you will want to get an adult to help.

When it starts to snow, take your box outside and catch snowflakes on the black paper. If you need to, you can move them around to look at them with the paintbrush or toothpicks. Look at them with the magnifying glass. A magnifying glass works best if you hold it close to your eye and move the paper with the snowflake up close to get it in focus. Try not to breath on the snowflake or it might melt. How many sides does a snowflake have? Do all snowflakes seem to have this same number of sides? Does the size and beauty of snowflakes change with the weather? How can you find out?

A Vermont farmer, Snowflake Bentley, photographed snowflakes for years. Click on his nickname to see some of the pictures he took and to read about him.

For some beautiful snowflake images visit EarthmatriX.

For more images and information about how snow forms as crystals visit Snow Crystals.

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.

The purpose of this experiment is to learn about the snow flakes, their shape and their importance.

or you may select any of the following questions for your project.

1. How can we test the snow and why? (experiment 3)

2. How can we watch the structure of snow flakes using a magnifier or microscope? (Experiment 4)

3. What factors affect the shape of snow flakes. (experiment 2)

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. (For higher grades only)

Independent Variable that may affect the shape of a snow crystal is the temperature.

Dependent variable is the shape of snow flake.

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. Following are sample hypothesis for the questions that we have proposed:

Note: You can modify the questions and hypothesis as you need.

Question: How can we test the snow and why? How much water can we get from each gallon of snow?

Hypothesis: Since snow is valuable for it’s water content, we can test the snow by determining its density or water content. I think the density or water content of snow varies depending on the type of snow.

Question: How can we watch the structure of snow flakes using a magnifier or microscope?

Hypothesis: We can collect falling snow flakes on a cold surface for observation. We may also be able to preserve the snow flakes by using adhesive sprays.

Question: What factors affect the shape of snow flakes.

Hypothesis: I think the air temperature and the speed of formation affect the shape of snow flakes.

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:

Gathered information indicated that all snow crystals are hexagonal or have 6 sides. In this experiment we will make models of snow flakes from paper.

Procedure:

Start with a square sheet of paper. Remember, a square has 4 equal sides.

Experiment 2:

(only for higher grades and students that are being helped by an adult)

The purpose of this experiment is to simulate the same conditions that forms snow flakes inside a closed area, so we can produce snow crystals in any season for our observation or research.

Material:

• • One used 20-oz plastic Coke bottle
  • Three large-diameter Styrofoam cups
    (or something similar; see below)
  • A small kitchen sponge (1/2 inch thick)
  • A short length of nylon fishing line
    (thinner is better; 1-pound test is good)
  • A strong sewing needle
  • Four straight pins
  • One paper clip
  • Some paper towels
  • 10 lbs Dry Ice*

Procedure:

1. After rinsing out the Coke bottle, use a sharp knife to cut the bottle in two, about 1/2 inch above the bottom, as shown in the figure. Poke a hole in the center of the bottle bottom using the sewing needle, and also poke four holes in the side of the bottle bottom. Make a small round sponge to fit inside the bottle bottom, and hold the sponge in place by putting the four straight pins into the side holes you made (see figure).

2. Thread the fishing line into the sewing needle, and push the needle through the hole in the bottle bottom, and through the sponge. Attach the fishing line to the bottle bottom with a piece of tape, and tie a knot in the other end to hold the paper clip. When the Coke bottle is inverted and reassembled, the string should swing freely inside the bottle, as shown in the figure.

3. Place the inverted Coke bottle inside the three Styrofoam cups, as shown, so that the bottom of the Coke label is at the same height as the top of the cups (see figure). There should be about one inch of clear space between the sides of the Coke bottle and the top edge of the Styrofoam cups.

4. Put the dry ice inside two plastic grocery bags, and pound on it with a hammer (or other blunt object) to crush the dry ice. This works best on a hard surface, like concrete or asphalt. Dry ice is much softer than water ice, and it crushes very easily. Put the crushed dry ice back into its Styrofoam cooler, and use a spoon to transfer some into the Styrofoam cups around your chamber (see the figure). Fill the cups to the top, and cover with a piece of cardboard cut to shape, or with some paper towel strips. It’s also a good idea to wrap some paper towels around the top of the Styrofoam cups, to keep them from “sweating.”
5. Pull the top off the chamber (the bottle bottom + sponge), wet the sponge with tap water, and replace.
6. Observe! Small ice crystals should begin forming on the string after 5-10 minutes, and after 20 minutes you should have a pretty good bunch of crystals. A magnifying glass is useful, but not essential for crystal viewing. When things get crowded, you can pull the top off the chamber, wipe the string clear with your fingers, and try again. You should also knock the crystals off the walls of the chamber — swinging the paper clip around accomplishes this nicely. One charge of dry ice will last about six hours, and more can be added as needed.

Sample crystal:

If you look closely, you can observe both needle-like and plate-like growth in your growth chamber. The easiest forms to identify are the dendrites that form at -15C, especially if you let the crystals grow to a large size. Above those will be the fish bones, which are a type of needle growth that grows at -5C.

Experiment 3:

Snowflakes are formed by the freezing of water vapor in the air. Layers of snowflakes on a surface, such as the ground, are simply called snow. Snow is mostly a combination of snowflakes and air. The amount of air that snow contains affects its volume (the amount of space it takes up). When snow melts, the trapped air is released. Thus, the volume of snow is greater than the volume of the liquid water it forms when melted. Not all snow is the same. The ratio of the volume of snow to the volume of liquid water that the melted snow forms is not the same in all snow samples. In this experiment we will test one snow sample and calculate the volumetric ratio of water to snow.

Question is: How does the volume of snow compare to the volume of liquid water that the melted snow forms?

Hypothesis: Make a guess about the amount of water you think a cup of snow will form when melted. Half as much? One-third as much? How much?

Material:

• • pencil
  • ruler
  • 1 sheet of paper
  • permanent marker
  • three (3) 10-oz (~300ml) clear plastic drinking cups (We suggest using 10 oz. clear plastic picnic cups that come from the same package, although other size cups will work. You need three because we will be finding average values)
  • tap water
  • volume measuring device ( graduated cylinder or metric measuring cup 750 ml (3 cups) snow (use shaved ice, crushed ice or accumulation of frost from a home freezer as alternatives if snow is not available.)
  • spoon

Procedure:

1. Use the pencil and ruler to prepare a data table on the paper similar to the one in Scoreboard below.
2. Near the bottom edge of each cup, use the pen to label the cups A, B, and C.
3. Put 250ml (1 cup) of unpacked snow into each cup. Use the spoon to help remove the snow from the cup,but take care not to press the snow flakes together.

4. Record the volume of the snow, which should equal 250ml (1 cup), where you found it (your town, city, or locale), and a description of the snow (i.e. 3 day old snow) in the data table. (If you have access to a scale, also measure the weight of each cup before and after filling it up with snow.)
5. Draw a line and mark the snow level with an S (for snow) on each cup (all 3 should be the same).

6. Set the cups on a table indoors and allow the snow to melt.
7. When all of the snow has melted mark the water level on all three cups Sw (for snow water).
8. Pour the water from cup A into your measuring device. Record the volume of the water in the data table.

9. Determine the ratio between the volume of the snow and the volume of the water. Do this by writing a fraction with water volume as the denominator and snow volume as the numerator (ratio = Snow Volume/Water Volume ). Express the answer as a decimal by dividing the denominator into the numerator. Record the answer. (Note: the answer tells you how many time greater the snow volume is than the volume of the melted water it forms.)
10. Repeat steps 6,7 & 8 for cups B & C.
11. Determine the average ratio and record. Do this by adding the ratios and dividing by 3.

Results:
Create a table like the one below and record your data.

If you used a scale to weigh the cups of snow, weigh them again after the snow is melted. Does melting change the weight of snow.

Experiment 4:

In this experiment you will catch, watch and preserve snow flakes shape.

Material:

• • black velvet or black construction paper
  • Magnifying Glass
  • Snow

Since snowflakes melt so quickly you need to freeze your cloth or paper. Have it ready frozen and ready to go for the next snowfall, and go outside and let some snowflakes land on the dark surface. Quickly, before they melt, examine the flakes with a magnifying glass. Many snowflakes are “broken” and so you don’t see the whole six-sided crystal, but with persistence you’ll see some beautiful examples.

Keep Some Snowflakes

What you will need:

• • Piece of glass (or microscope slide)
  • Hairspray (aerosol, NOT pump)
  • Snow

You can have a permanent record of your caught snowflakes if you freeze a piece of glass and the hairspray before the next snowfall. (Both may be stored in the freezer until you need them.) When you’re ready to collect some snowflakes, spray your chilled glass with the chilled hairspray and go outside and let some snowflakes settle on the glass. When you have enough flakes bring the glass indoors and allow it to thaw at room temperature for about 15 min. Now you have a permanent record of your snowflakes!

Make a graph:

Make a bar graph to show how many of each shape snowflake did you catch. Make one vertical bar for each shape. The height of each bar represents the number of flakes you caught with that specific shape. Under each bar write the shape it represents.

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:

Experiment 3 needs some calculation to calculate the ratio of snow volume to water volume.

Summery 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.

As a display project you will not need a data table or graph.

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