9 March, 2002
Weekly Poker Flat Trip Martin, Lynette and I went to Poker
Flat with three Fairbanks teachers to do the weekly measurements on
four ponds: MST, 31.6, 33.5, and Jalpertia. As sunny as it usually
is, the wind traversed over Poker Flat at the speed of 25 mph
bringing down the wind chill to ~5 F.
Let's Talk Science: Density Review On March 5th, I provided a
brief explanation on snow density. To review, we need two
measurements to calculate density: snow samples and snow depth. The
formula for density is mass per unit volume (D=M/V) and is expressed
in g/cm3. Before we can proceed with the formula, we must find the
volume of the snow sample. Volume is pi r2 h. The value for pi r2
is 21.711909 cm2, we multiply this value to the snow depth (h). Below
are two measurements from today:
P1: 91.3 g / 21.711909 cm2 x 24.5 P4: 109.9 g / 21.711909 cm2 x 32
For answers, refer to March 10th journal entry.
Ice Thickness Ice thickness (Zi) is measured using either two
methods: drilling or hot wire gauge. For a diagram and more
information on hot wire gauges, refer to the January 24th journal
entry.
Drilling Measurements are taken using a metal rod and meter stick.
Hot wire gauge A long resistance wire is attached to a metal
toggle through the Lshaped, aluminum tube that is staked into the
ice. L1 and L2 measurements are added and then subtracted from the
total length.
What are the ice thickness calculations for the following
measurements? Total Length = 245 cm
1. L1 = 104 cm, L2 = 53 cm 2. L1 = 134 cm, L2 = 48 cm 3. L1 = 123 cm,
L2 = 39 cm
See below for answers
1. Carol, middle school teacher takes base temperature.
2. Snow sample from P1.
3. Snow sample into plastic bag.
4. Metal rod used to measure ice thickness (Zi) Ice Thickness Answers 1. 88 cm 2. 63 cm 3. 83 cm
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