# Snow Weight - Area (polygon)

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Equation / Last modified by KurtHeckman on 2018/08/17 19:56
M =
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KurtHeckman.Snow Weight - Area (polygon)
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The Weight of Snow on a Polygon calculator computes the approximate weight of snow on an POLYGON area (e.g. deck) based on the dimensions of the polygon (number of sides of the polygon and the radius) and the depth and type of snow. Geometric Polygon

INSTRUCTIONS: Choose units and enter the following:

• (n) The number of sides of the polygon
• (r) The radius of the polygon (from the center to any apex).
• (d) The depth of the snow
• (sT) Choose the type of snow from the list.

Weight of Snow (M): The Weight / Mass of the Snow is returned in kilograms.  However this can be automatically converted to other weight and mass units (e.g. pounds or tons) via the pull-down menu.

#### The Math / Science

Snow Water Equivalent (SWE) is the product of snow depth and snow density. It can be presented in units of either kg/m2 or m:

SWE ((kg)/(m^2)) = snow depth (m) x snow density ((kg)/(m^3))
SWE (m) = snow depth (m) x snow density ((kg)/(m^3)) / water density ((kg)/(m^3))

You can calculate snow depth from SWE if you know the density of the snow.  Od course, density of snow can range anywhere from 5% when ambient air temperature is 14 F, and can range up to 20% if the temperature is 32 F.

The snow density will increase after the snowfall due to gravitational settling, packing, wind effects, melting and refreezing.

 Type of snow or ice densities (kg/m³) New snow (immediately after falling in calm) 50-70 Damp new snow 100-200 Settled snow 200-300 Depth hoar 100-300 Wind packed snow 350-400 Firn   (granular snow) 400-830 Very wet snow and firn 700-800 Glacier ice 830-917

The equation will use a median value for the ranges in the density value column.