from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A resistor made of semiconductors having resistance that varies rapidly and predictably with temperature.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a resistor whose resistance varies rapidly and predictably with temperature and as a result can be used to measure temperature.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a semiconductor device made of materials whose resistance varies as a function of temperature; can be used to compensate for temperature variation in other components of a circuit
Maybe what you have is a thermistor, which is not linear.
That could be either good or bad depending upon the kind of thermistor and the mass that it is attached to.
The probable reason for this: "poorly-situated" stations are predominantly MMTS (aspirated thermistor) sites which have a known cool bias compared to the Liquid in Glass stations (which tend to make up the "well-sited" sites.)
The new system is thermistor-based with a “beehive like” instrument shelter, whereas the older systems consisted of liquid-in-glass thermometers, mounted inside a Cotton Region Shelter Stevenson Screen.
The NWS has replaced a majority of the liquid-in-glass thermometers in wooden Cotton-Region shelters with thermistor based maximum-minimum temperature systems MMTS housed in smaller plastic shelters.
These are thermistor sensors, so in practice the error would be a constant offset from reading to reading, closing that 3 degree window down to +/- 1 degree.
Is the temp sensor a glass thermometer or a thermistor?
A hybrid should be developed that uses a mechanical thermometer that is read electronically rather than a thermistor element that is subject to drift and noise.
I was looking for something subtle like thermistor drift but what you describe is classic FUBAR.
In other words every thermistor needs its own calibration if it is to be accurate .02 C is possible over wide ranges.
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