Since 9th Feb I have been noting down the simultaneous temperature of pre-dawn air coming in my front door compared to Canberra Airport ~13km away as a crow might fly.
We are not that far from Hall, near farmland to the west and about 100m higher than the airport so in theory we might expect to be 0.64°C cooler. The front door faces east into a suburb and it so happens that most mornings a noticeable breeze comes in the door when opened.
I expected the vagaries of weather would produce a few days when we were cooler than the airport. It turned out that only on one day 16 March were we 0.2 cooler than the airport and that morning was blowing a warmish nor-wester at 16C – the wrong direction for the front door so I took a reading in the yard in full breeze.
Anyway – here is the chart, of suburban air temperature read in the dark minus the Canberra Airport reading off the www. Days of greater contrast tend to have clear skies – rainy days tend to show the least contrast. Average contrast over the 75 days – 3.7 degrees.
I wonder if readers ever try similar comparisons in their local region.
Note my thermometer is a little battery powered “thermistor” gadget with a metre of wire, digital readout to 0.1deg – which I had calibrated informally against two liquid in glass thermometers.