This weather station is located in Mt. Baldy Village on Central Avenue, close to the Post Office and Fire Station on Mt. Baldy Road. The weather station's sensors are 1-Wire devices mastered by an Embedded Data Systems HA7Net Bus Master, and polled by the
ha7netdsoftware running on a Sun Fire V120.The outdoor sensors are mounted four feet above the ground and shaded from direct sunlight in an aspirated enclosure.
Note that the station is located at an elevation of 4206 feet above mean sea level. The "4000 feet" sign nearby on Mt. Baldy Road is clearly in error as can be seen with the Mt. Baldy, Calif. USGS Quadrangle or a GPS unit.
Outdoors 1 Temperature and slow response relative humidity (Embedded Data Systems HMP2001S) Temperature: ± 0.5°C (± 0.9°F)
Relative humidity: ± 5%This sensor is an Embedded Data Systems HMP2001S which provides a temperature corrected relative humidity measurement. The underlying temperature measurement is made with a Dallas Semiconductor DS18S20 "High-Precision 1-Wire Digital Thermometer". The device used to measure the relative humidity is unknown. A DS2406 is used to communicate with the relative humidity device.
Outdoors 2 Temperature and fast response relative humidity sensor (AAG TAI 8540-A) Temperature: ± 2.0°C (± 3.6°F)
Relative humidity: ± 5%The sensor, an AAG TAI 8540-A, reads a temperature corrected relative humidity. The temperature measurement is made via a Dallas Semiconductor DS2438 "Smart Battery Sensor", while the relative humidity is read from a Honeywell HIH 3610-A humidity sensor via the A/D converter onboard the DS2438.
Indoors Temperature and atmospheric pressure sensor (AAG TAI 8570) Temperature: ± 0.8°C (± 1.4°F)
Pressure: ± 1.5 mbar (± 0.04 in Hg)This sensor is an AAG TAI 8570, a device capable of reading both the ambient air temperature as well as the atmospheric pressure from 300 to 1100 mbar. The sensor contains two Dallas Semiconductor DS2406 "Dual Addressable Switches" and an Intersema MS5534A "Barometer Module" capable of measuring both temperature and pressure. Intersema's recommended first and second-order temperature corrections are applied to the pressure read from the MS5534A [1]. The pair of DS2406s are used to convert between 1-Wire and 3-Wire protocols.
The reduction of station pressure to mean sea level is accomplished as per "Determination of Height by the Barometer and Reduction of Pressure to Fixed Levels" [2]. In keeping with US convention, the mean temperature t_s in equation (7) is taken to be the mean of the current and the 12-hour previous ambient outdoor air temperature. The lapse rate L is as per the 1976 US Standard Atmosphere. Finally, bilinear interopolation is used to determine the correction for humidity C from Table 48A [2]. The average of the fast and slow outdoor relative humidity measurements and associated temperatures are used to determine the vapor pressure as per Bolton, 1980 [3].
The Cow Canyon Saddle clear sky clock visually summarizes astronomical viewing forecasts for the next two days at nearby Cow Canyon Saddle. The forecast comes from the Canadian Meteorological Center and is specifically designed for astronomers. This particular rendition of that forecast is made available by fellow astronomer Attilla Danko.
To see the sky clock, direct your browser to http://cleardarksky.com/c/CwSddlCAkey.html .