Below we're measuring temperature without really knowing what we're doing. * Why read the manuals, why study detailed physics beforehand? Theory is more fun with practical results in your hands; no matter how crappy they are. Start bottom-up and learn by failing. This is just a game of (re-)discovery, nothing is at stake here.
Differences between the sunny and the shadow side of street objects measured with different devices on different dates:
a) Measurements with an infra-red thermometer on 4 february 2012 near noon. Air temperature (digital electronic thermometer) was -4 degrees Celsius. Temperature of snow surface (infra-red thermometer) was -10.4 degrees. Official measurements by the KNMI: Mean -8.1 Max -3.6 Min -14.2 °C.
b) Measurements with an infra-red thermometer on 11 february 2012 near noon. Air temperature (digital electronic thermometer) was -2.6 degrees Celsius. Official measurements by the KNMI: Mean -7.6 Max -2.8 Min -13.2 °C.
c) Measurements with the thermocouple on 11 february 2012. Air temperature (thermocouple) was +3 +4 degrees Celsius.
* Somehow I cannot avoid using the scientific convention of talking about "we" - "I" feels unnatural in this context.
* And in the meantime I've discovered that I've made serious errors in my measurement method. The infrared thermometer should be used differently.
|Plane tree - emissivity 0.98 - sunny side :
b) -2.8 -0.5 +2.2
c) +10 +11
|Plane tree - shadow side :|
b) -6.7 -9.1 -9.2 -10.1
c) +8 +9
|Brick wall - emissivity 0.93
Sunny side - sun perpendicular to wall
Brick wall - semi sunny side - sun parallel to wall :
Brick wall - shadow side :
|Painted iron lamppost - sunny side:
b) -3.6 -5.1
Painted iron lamppost - shadow side:
a) -5.7 -6.1
b) -7.4 -7.8
|Enameled steel dustbin - sunny side:
b) -1.8 +0.7
Enameled steel dustbin - shadow side:
b) -8.6 -10.1
|Concrete street curb - emissivity 0.94
Sunny side - sun perpendicular to surface:
Concrete street curb - semi sunny side
sun parallel to surface :
Concrete street curb - shadow side
a) -10.4 -11.2
|Concrete street pylon - sunny side :
Concrete street pylon - shadow side :
a) -7.4 -7.3 -7.2
Official weather measurements by the KNMI
Introduction to infrared thermometers - it's more complicated than you would think - and I've made serious measurement errors - see the illustration
Infrared Thermometer Emissivity Tables - this does not change the results very much
Emissivity measurements - extremely detailed and interesting
Tree Thermography + tree emissivity