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Snow Science
Snow Density
Gathering and measuring the density of snow
Theme: Data Presentation
Content Area: Earth Sciences
Grade Level: 2-6
Materials Needed:
- Deep snow
- Little Bear Snowshoes
- Three large buckets or liquid containers the same size with lids
- Measuring cups
- Handouts
Learning Goals:
At the completion of this unit, students should be able to demonstrate their understanding of data collection, measurement, charting and analysis by:
- Participating in the data collection activities
- Completing the Data Record handout
- Drawing their own Data Presentation Chart
Background:
In many places, government water engineers and farmers depend on winter snow to provide an adequate water supply for cities and farms.
These people watch and measure the amount of snow all winter long. It is not just the depth of the snow that is important, but the amount of precipitation or, in other words, the amount of water in the snow.
You can measure the amount of water in snow by collecting some the snow, melting it, and measuring the water. Some snow is very dense, which means it contains a large quantity of water for its relative size. An example might be that one gallon of snow, when melted, becomes one quart of water. Other snow has a very low density. In this case, a gallon of snow makes only a cup of water.
Many things affect the density of snow including: temperature, air pressure, the nature of the storm, your geographic location and altitude, etc.
In truth, each snowstorm brings snow of a different density.
In this unit, students are the weather watchers. They must determine how much moisture is available in the snow in their area. This experiment does not require you to track precipitation for a complete season. The best time to do it, however, is during the biggest snow weeks when there is lots of activity in the weather.
Density:
The amount of space between molecules or particles of any substance is what determines its density. Lead is more dense than aluminum which is more dense than wood which is more dense than foam rubber which is more dense than styrofoam. Density is equal to the mass (or weight) of a substance divided by its volume (d=m/V). The metric system was set up in such a way so that the density of water can be written as 1 gram per milliliter (1g/mL). One mililiter (mL) is also equal to one cubic centimeter.
Precipitation:
The word precipitation is defined as any form of water that falls from clouds and reaches the ground; the amount being expressed in inches of liquid water depth. For this activity, we will compare not the depth, but the volume of the snow or water. Water is "pure precipitation." Snow, on the other hand, is mostly air. As you can see, the density of snow is related to the measure of the water in snow. The density of snow might be expressed as 1 cup of water per gallon of snow or 100 mL/L [density=V(water)/V(snow), where V=volume.]
Learning Activities:
Introductory Discussion:
Explain the concept of density. Examples are especially helpful.
Allow the students to hold a brick and a block of wood or foam rubber the same size.
Use an illustration to show something that is loosely filled with particles versus something that is tightly filled with particles. A fun activity is to have the children stand together in an area and give them instructions to space apart or bunch together to show the realities of high and low density.
Ask the children how much water they use at home. Make a list on the board of all the things we use water for. Ask them where the water comes from. Talk about how the winter snow fills up our rivers, streams, and reservoirs for use in summer. Explain how forecasters measure snow and precipitation to determine how much water will be available in summer.
Preparation Activity:
Using the buckets for the experiment, fill one with water, one with snow, and leave the last empty (filled with air). Cover the containers with lids to avoid spills. Show how each has a different density. Discuss how the snow, once melted will no longer fill the bucket completely. Explain that by measuring the water from melted snow, you are actually measuring the amount of percipitation.
Field Trip:
Using snowshoes, take the class into the deep snow.
You have three buckets. Use one to collect snow from the surface. Avoid compressing the snow as you collect it. (This can be difficult, but the activity will work regardless of the collection methods used.) In the second bucket, collect snow from deep beneath the surface. The final bucket is to be used more like an actual forecaster might use it. Find a place where you can leave the bucket to collect falling snow. On the first day, you will not have data for this bucket, unless you make arrangements to leave it out the day before.
Cover the containers and take them inside to melt. Each day (or whatever time interval you choose) you will repeat this field trip activity. Be sure to plan ahead to guarantee that your collection methods can be repeated for at least 10 time intervals.
Using Handouts:
Once the snow is melted, measure the water in each container and ask the children to record the information on their Data Record handout.
Presenting The Data:
Using the handout on Making A Chart and the completed Data Record handout, assign the students for make their own Data Presentation Chart.
Learning Assessment:
A Snow Density Quiz has been provided as a possible learning assessment method. Use the quiz as best fits your student's needs.
Handouts:
Variation:
The point of this experiment is to have the children collect data over time, but you could change it to measure data by location or some other variable.
Two possible methods for measuring data over time that can be done in a single day are:
- Fill a very tall container with snow and take depth measurements every 5-10 minutes and chart the melting speed.
If you can find snow of different densities, you can compare the melt speed for each.
- On a day when it is snowing, place a yard stick outside and measure snow depth every 30 minutes throughout the day.
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