[wxqc] Measuring Snow

[Mark Wyman]

As for melting: Use a deep-cycle lead-acid battery to store solar energy for
the stormy days, some method of detecting the weight of liquid in your gauge
(strain gauge on an arm that carries the weight of your sensors), and then
turning on the heater until the weight lets up. This will get you readings
during a storm, and allow the tube to be smaller in length. However it would
be good to determine how much energy is needed to melt 5ft of snow at what
the typical low storm temperature is. Then your battery should store 2x
this. You should insulate the gauge as well.
	You also need to regulate the temperature of the heater so that you
don't loose precipitation to evaporation from having too warm of a surface,
say just get it to 35 degrees and stop heating, wait till it gets to 33,
check weight, if still heavy turn element back on, empty weight, turn it
off. Would have to experiment with temperatures a bit. Some 12V automotive
lightbulbs spread about on the inside of the rain gauge would be excellent
heaters, and would warm all of the surfaces, including the gauge, where you
don't want ice to form.
	Just have to hope the birds don't discover that by resting on your
gauge that they will get warmed toes.
	Looks like you may have enough solar panels to accomplish this.


One other thought, are you sure there isn't ice on the measurement system
causing errors? While your tube may be warm, the sensor may not be.

-Mark

-----Original Message-----
From: wxqc-bounces at lists.gladstonefamily.net
[mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Mark Wyman
Sent: Wednesday, January 04, 2006 3:25 PM
To: 'Discussion of weather data quality issues'
Subject: RE: [wxqc] Measuring Snow

	The only things I can think of is there is a hole in the glue,
allowing water to cascade down the side of the pipe and collect in the glue
joint, then drip through the hole adding to the total. 
	The most remote of ideas has to due with Ventura Effect, where air
blows over an orifice causing it to oscillate. The air oscillation could
bring in more droplets of water than would be seen otherwise. To stop the
oscillation would be tricky, and I am not sure how to accomplish this.
	Otherwise you may just be experiencing orography effects like you
suggest. 3 miles from me to the south gets about 25% more rain in the summer
than we do, and this last year, areas 5 miles to our west got 150% more. We
live in hills, but our proximity to the lakes causes a surprisingly huge
impact on rain quantity.
	The only way to really verify your setup is to set a manual
collector next to it and later compare the two, you cannot rely on the
precip readings of a neighbor 3 miles away to verify your readings.

	-Mark

-----Original Message-----


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