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Show At present, not all Class A ski areas have a recording precipitation gage, but the aim is to equip most of these areas with such a gage. The recording precipitation gage ( B14) is a self- contained unit with an 8" orifice, identical to that of the standard rain gage ( A20a), a funnel, and a collection bucket which rests on a weighing mechanism. The weighing mechanism is connected to the pen of a recorder with a drum- mounted chart. For winter records of precipitation in the form of snow, the funnel is removed so the snow can fall directly through the orifice and into the bucket. Canopying or plugging of snow can constrict or block the orifice. This problem can be minimized where electric power is available by wrapping an electric heating cable ( 75- 100 watts) around the lower part of the orifice just above the bucket. The exact arrangement of the heater and the amount of power required vary with temperature and snowfall intensity. It has to be adjusted by trial and error for each particular climate. No completely satisfactory solution has been found. Experiments with propane heaters have had only limited success with this type of gage. In the absence of electric power, the occasional plugging of the gage and loss or distortion of the precipitation record has to be accepted. Frequent attention and maintenance during heavy storms are essential in any case. In normal operation this recording gage is used with a chart and drum that rotate once every 2k hours. Ideally a fresh chart should be installed each day, but it is permissible to leave a single chart in place for several days during dry periods or as long as the precipitation record remains clear. Preferably a fresh chart should be installed at the start of major precipitation periods. The collection bucket is normally charged with one quart of permanent- type anti- freeze and two ounces of SAE 10 motor oil. The anti- freeze causes the snow to melt and the oil inhibits evaporation. After about 3" of precipitation ( water equivalent) have accumulated in the bucket, it is dumped and recharged. The recharging can be kept a simple operation if 1- qt. cans of antifreeze ( and a can opener) are stored adjacent to the gage along with a container of oil. Another type of recording precipitation gage is the heated tipping bucket gage ( B15a and B15b). The 8" orifice of this gage is heated by electrical power, if available, or by propane. Snow is thus melted to water and is collected in a small metal bucket. When the volume of water in the bucket reaches .01", the bucket tips over closing an electrical contact. The gage is connected by cable to a remote event recorder. The " event" is the closing of the electrical contact that occurs with each tip of the bucket; hence, the recorder provides a continuous trace of precipitation in discreet .01" increments. 23 |
