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Inside the Snow Shelter: Light and Sound in Winter Camp

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Inside the Snow Shelter: Light and Sound in Winter Camp

Model how snow, fabric and ice reflect, absorb and transmit waves.

Light on the snow

Read the trip notes and Table 1, then answer the questions.

Trip Notes: A Night in a Snow Shelter

1Each February, the Bramble Lake Winter Field School takes a group of eighth graders on a two-day snow camp. On the first morning, guide Ms. Henrietta Vu showed Saskia Delmonte, Ifeoluwa Strand and their group how to build a quinzhee, a snow shelter. They piled snow into a large mound, let it settle for two hours, then dug out a room inside while Ms. Vu checked the wall thickness with sticks pushed in from outside. Most of the wall ended up about 30 cm thick, with one thin spot about 10 cm thick. Ms. Vu also poked a small air hole through the roof and made sure no one worked inside the shelter alone.

2Ms. Vu told everyone to wear sunglasses on sunny days, because the snow can send a lot of light into the eyes. At noon, Saskia used a light meter to test this. With the meter pointing straight up in the open, it measured the sunlight reaching the ground. With the meter held 30 cm above a surface and pointing down, it measured the light that came back up off that surface. Inside the shelter and the tent, she pointed the meter at the wall (Table 1). The gray snow by the parking area was dusty, and by late afternoon it had softened and partly melted, while the fresh snow nearby looked almost unchanged.

3Ifeoluwa ran a sun test on two fleece squares of the same size and thickness, one black and one white. He laid each on the snow in full sun with a thermometer under it. Both thermometers read −6 °C at the start. After 20 minutes, the one under the black fleece read 8 °C and the one under the white fleece read −2 °C.

4In the afternoon, the group tested sound. A small speaker played the same steady tone at the same setting for every reading, and a sound meter 2 m away measured the sound level in decibels (dB), with or without a wall between them (Table 2). Out on the frozen lake, Saskia clapped toward an icy rock cliff across a small cove and heard a sharp echo. When she clapped toward a tall bank of fresh, fluffy snow, she heard no echo.

5That night, the group slept warm in the shelter while the air outside dropped well below freezing.

Table 1: Light Meter Readings at Noon
Where the meter wasReading (lux)
In the open, pointing up at the sky50,000
Pointing down at fresh snow42,000
Pointing down at old, gray snow25,000
Pointing down at the dark green tent4,000
Inside the tent, at its nylon wall7,500
Inside the shelter, at the 10 cm spot6,000
Inside the shelter, at a 30 cm wall100
1.
Use Table 1. Compare the light coming back up off the fresh snow with the sunlight reaching the ground.

The fresh snow reflected about % of the sunlight that reached it.

2.
Use Table 1 and paragraph 2. Why did the meter read less above the old, gray snow than above the fresh snow?
Question 2 options
3.
Use Table 1. Compare the two readings inside the shelter.

The reading at the 10 cm spot was times the reading at the 30 cm wall.

4.
Which model best describes what happened to most of the sunlight that hit the outside of the shelter's 30 cm wall?
Question 4 options
5.
Use paragraph 3 and Table 1. Which conclusion does the fleece test support best?
Question 5 options

Sound in the snow

Use paragraph 4 and Table 2 to answer the questions.

Table 2: Sound Meter 2 m From the Speaker
SetupSound level (dB)
Open air, above fresh powder68
Open air, above icy lake crust71
Inside the tent, nylon wall between66
In the shelter, 30 cm snow wall between44
6.
Use Table 2. Compare the reading inside the shelter with the open-air reading above fresh powder.

The snow wall lowered the sound level by dB.

7.
In the open air, why was the reading higher above the icy crust than above the fresh powder?
Question 7 options
8.
Compare the tent and shelter readings in Table 2 with the open-air reading above fresh powder. Which model fits both walls best?
Question 8 options
9.
Sort each observation from the trip by the wave behavior it shows most.
10.
Ifeoluwa says, "Snow is light and fluffy, so a snow wall lets light and sound through about as well as a tent wall does." Do you agree? Write a claim, give evidence from both tables, and explain your reasoning using the words reflect, absorb and transmit.