ECOWITT HP1000SE PRO, Manual

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71
other weather stations) are not a good source and have their own
margin of error. Using a local weather station in your area is also a
poor source due to changes in location, timing (airport weather
stations are only updated once per hour) and possible calibration
errors (many official weather stations are not properly installed and
calibrated).
Place the sensor in a shaded, controlled environment next to the
fluid thermometer, and allow the sensor to stabilize for 3 hours.
Compare this temperature to the fluid thermometer and adjust the
console to match the fluid thermometer.
(2) Humidity is a difficult parameter to measure electronically and drifts
over time due to contamination. In addition, location has an adverse
affect on humidity readings (installation over dirt vs. lawn for
example).
Official stations recalibrate or replace humidity sensors on a yearly
basis. Due to manufacturing tolerances, the humidity is accurate to
± 5%. To improve this accuracy, the indoor and outdoor humidity
can be calibrated using an accurate source, such as a sling
psychrometer.
(3) The display console displays two different pressures: absolute
(measured) and relative (corrected to sea-level).
To compare pressure conditions from one location to another,
meteorologists correct pressure to sea-level conditions. Because the
air pressure decreases as you rise in altitude, the sea-level corrected
pressure (the pressure your location would be at if located at sea-
level) is generally higher than your measured pressure.
Thus, your absolute pressure may read 28.62 inHg (969 mb) at an
altitude of 1000 feet (305 m), but the relative pressure is 30.00 inHg
(1016 mb).