Climate data for C1 chart recorder, 1952 - 1982.

Climatological data were collected from a Niwot Ridge climate station (C1 at 3018 m) throughout the year. Parameters measured were temperature, relative humidity, solar radiation, precipitation, barometric pressure, and wind speed. The station was initially instrumented with a thermohygrograph (regularly calibrated and checked with maximum and minimum thermometers and psychrometers), which was equipped with a Bourdon tube (to measure temperature) and a banjo-spread hair element (to measure relative humidity). The thermohygrograph was situated in a white, all wood, louvered Stevenson screen which is oriented with the door facing north. The station was initially instrumented with a standard 8-inch precipitation gauge installed with the rim 1 m above ground. A recording precipitation gauge was installed in 1962, with the installation in the clearing positioned so that the gauge rim subtended an angle of 45 degrees to the tree crowns although the most effective angle is 30 degrees according to Leaf (1962). Precipitation was caught in a bucket containing ethylene glycol (to melt snow) and light oil (to prevent evaporation). As the weight of the bucket increased, a pen moved up via a spring mechanism and recorded on a rotating chart. Solar radiation was recorded on a bimetalic strip mechanical actinometer. Ninety percent of solar radiation from 360 to 2000 nm was transmitted through the instrument's glass dome. Barometric pressure was recorded on a Friez microbarograph at the Mountain Research Station at 2880 m. The instrument was calibrated against a full-range mercurial, Fortin-type barometer. The station was initially instrumented with a totalizing anemometer (approximately 0.7 m above the general level of tree crowns). Wind speed (peak gust) was subsequently measured with a 3-cup, AC-generating anemometer that continuously recorded onto an Esterline Angus strip chart recorder. Wind direction was recorded as a pen position on a continuously recording strip chart. The thermohygrograph, rain gauge, actinometer, and microbarograph all used wind-up or battery-driven clock drives that rotated the recording chart on a right cylindrical drum with a fixed period between 24 h and 861 h depending on the gears used. These clock mechanisms were virtually identical and therefore completely interchangeable among the instruments.