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→How do I get good temperature and humidity measurements: explaining colours
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== How do I get good temperature and humidity measurements == | == How do I get good temperature and humidity measurements == | ||
The international standard states ambient temperature/humidity is measured at 1.25 metres above ground level, protected from direct sun radiation (and direct rain), unless you are measuring soil or ground temperatures. Modern Stevenson Screens are uPVC constructed with a black interior and a white exterior. | The international standard states ambient air temperature/humidity is measured at 1.25 metres above ground level, protected from direct sun radiation (and direct rain), unless you are measuring soil or ground temperatures. Modern Stevenson Screens are uPVC constructed with a black interior (so they do not radiate heat onto the sensors) and a white exterior (so they reflect as much radiation as possible). An air frost is defined as a temperature below the freezing point for water at this height. | ||
(If you are using a Fine Offset | There is a lot of discussion on the [http://sandaysoft.com/forum/viewforum.php?f=16 Homebuilt forum] about different approaches to improving measurements, and the problems with out of the box instrumentation from the different manufacturers. | ||
(If you are using a Fine Offset sensor, the thin depth of the thermonmeter/hygrometer should face where your receiver is, for maximum transmission strength, so the wide face is at right angles to the transmission route). | |||
== Pressure == | == Pressure == | ||
Varies with altitude and temperature, but no significant variation with spatial position with regard to nearby fixed bulky objects. Often measured indoors, only consideration will be trying to avoid any forced ventilation or extraction as such air moving systems could have different pressures on intake and outlet sides. Equally operation in close proximity to fast moving (road or railway) vehicles or tunnels can distort readings. | Varies with altitude and temperature, but no significant variation with spatial position with regard to nearby fixed bulky objects. Often measured indoors, only consideration will be trying to avoid any forced ventilation or extraction as such air moving systems could have different pressures on intake and outlet sides. Equally operation in close proximity to fast moving (road or railway) vehicles or tunnels can distort readings. | ||