Siting An Outdoor Thermometer & Hygrometer
Taking accurate temperature and humidity measurements is not as easy as you may think. Factors associated with solar radiation and other sources of heating and cooling can cause erroneous readings if your thermometer and/or digital hygrometers are not sited properly.
Temperature humidity sensors, often combined into one instrument on home weather stations (thermometer hygrometer), should not be sited in direct sunlight unless they are adequately protected by a solar radiation shield or placed inside a ventilated weather measurement tools housing. If that is not an option, the thermometer hygrometer sensors should be installed in a shaded location (such as the north side of a structure) and protected from rainfall (under the eaves but not too close to the roof is a compromise).
Ideally thermometer hygrometer weather sensors should be located in an open area and on level terrain - preferably above trimmed grass, which will allow for ventilation and air mixing between the sensor and ground. Avoid soil/dirt, natural groundcover, and rough or rocky terrain unless representative of your area. Steep slopes should be avoided also, as water and/or air flow induced by gravity could produce non-representative data. The standard height above ground for a thermometer hygrometer is five feet (1.5 meters).
If at all possible, keep the thermometer hygrometer away local sources of heating and cooling, and from nearby obstructions by a distance of at least four times their height. Be at least 100 feet (30 meters) from large areas of concrete and/or asphalt. Avoid sites where water or snow collects. DO NOT install the sensors under the shade of trees or vegetation.
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