Calibrations .. outliers and real data

Roland writes ..

"Interesting .. how is humidity measured .. not consulting google and from my really bad memory deconstructing a weather balloon that fell in my backyard (how about that as a learning opportunity) was this done by measuring the resistance across a thin piece of glass?"

Now -- of course -- we would use an industrial thermometer and a data logger shield on an Arduino. 

Data collected from 10 pm until 6 am.  The Arduino used a 9-volt battery. Note the wobble on the humidity data.  Perhaps a problem with the humidity algorithm. The data is comma delimited to allow easy analysis by any spreadsheet.