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Posted at 02:35 PM ET, 01/05/2012

Missing snow? Make your own ...

Dismayed by the bare winter landscape, Capital Weather Watcher Eric Peterson (eric654) has done what mother nature could not: produce snow at his home just over an hour from Washington (in Warren county). What follows is a guide to creating a winter wonderland in your own backyard, for as little as several hundred dollars.

Homemade snowmaking equipment blasts out snow Tuesday night (Eric Peterson)
Forget about the D.C. snowstorms that come once every five years or even reading the Capital Weather Gang forecasts. Now you can make your own snow exactly where and when you want it!! Well, not exactly everywhere and all the time, I’ll explain.

What equipment is required and what are the costs?

You need three pieces of equipment. A pressure washer, a compressor, and a snowmaking nozzle. A pressure washer (or power washer) costs about $100 and the compressor $350, but you may already own these as they have additional uses. The main expense is the snowmaking nozzle. I got mine for $400 from SnowAtHome (it includes adaptors to attach to the compressor and pressure washer) but I did not shop around at all. With a physics degree and machine shop you might be able to make your own nozzle.

SnowAtHome recommends a compressor with oil lubrication and I think I know why. The compressor I bought is not oil lubricated, and probably has teflon surfaces. That means it could wear out faster.

Equipment required for home snowmaking (Eric Peterson)
How does it best work?

The snowmaking nozzle (Eric Peterson)
The instructions say to get the biggest compressor that you can drag home and turn it on full blast. (Note how much bigger the compressor is compared to the pressure washer. ) The compressor uses the ideal gas law to do the most important work of snowmaking. The yellow tank (only partly visible above) is warm to the touch because the air is squashed inside and the molecules are bumping into each other more. When the air is released in the snowmaking nozzle, the expansion cools it greatly and the moving air also breaks apart the water droplets. Then, assuming there’s some nucleation magic (explained here) you get snow.

What weather conditions are required?

It needs to be cold and dry - this is really important. On Tuesday night, when we had lows in the teens and low relative humidities, Tuesday night’s snow quality was solidly in the “good” blue range on the handy chart from SnowAtHome .

Manmade snow from Wednesday night (Eric Peterson)
Last night (Wednesday), even with relatively dry 65% humidity and 28 degree air outside, the new snow was wet as it fell - in the “poor snow quality” range. The ideal gas law only goes so far in a non-ideal world and this snow did not have many minutes or even hours needed to coalesce, fall, and cool to the powdery consistency that (natural) sky-snow would’ve had.

What’s the snow consistency like?

Get ready to do some grooming. This snow is dense. Do not expect to fall backwards into it and make snow angels. It has the consistency of week-old snow in cool weather minus the icy crust.

But density may also be a plus. The snow is already pre-packed and should take longer to melt.

And it is not ice. It is real snow and makes a good sliding surface with a bit of give.

A large area of manmade snow generated Tuesday night (Eric Peterson)
How much snow can you expect to make?

The pile shown to the right from Tuesday night is about 10-12 feet wide and long and about 18-24 inches deep. But wait, there’s more. A bit more. The wind blew some around the yard, an inch or more in about a 30 foot radius.

Caution: note where you put the compressor and pressure washer because they might get covered (I protected mine with some plywood).

How much water and electricity is required, and at what cost?

The pile above took perhaps a few hundred to at most 600 gallons of water. My pressure washer can supposedly do 1.3 gallons per minute but I believe it does not run at full throttle. The well pump, compressor and pressure washer used about 20 kWh of electricity overnight at a cost of about two dollars. Well worth it.

Your accountant or spouse may also consider the cost of the equipment and amortize that into the snow cost. But the real point is there is at least 200 cubic feet of snow for two dollars, so a cubic foot of snow costs only one penny!

Note: you are advised to put the two motors (pressure washer and compressor) on separate electrical circuits. Putting them both on one 15 amp circuit tripped my breaker consistently (even the compressor alone tripped it once).

Can you hear me now?

Because the compressor runs all the time to make snow, it is loud. I don’t know how loud since I wear hearing protection outside. But inside, through some fairly sound proof windows, it generates the noise level of an old VW bug. I don’t think you would use this type of compressor in a suburban neighborhood. The pressure washer is a bit noisy too. Out here in Warren county, it is ok and an oil lubricated compressor might be a lot quieter (although I don’t know for sure).

It’s snowing!

The bottom line is that wet snow is still snow. Last night, the snowmaker ran for 3 hours with 3-6 inches over about a 12x12 foot area. It is really wet snow as they say on the chart, but “poor quality”?? Maybe if you are from Colorado, but not by D.C. standards.

By Eric Peterson  |  02:35 PM ET, 01/05/2012

Categories:  Capital Weather Gang, Latest, Science, Winter Storms

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