As published in “Geelong News” on 20-2-2001. Reprinted with permission.
Have you recently obtained a thermometer and are wondering where to put it? You can spend literally from two dollars to hundreds of dollars on an external thermometer or temperature gauge. The cheapest ones are usually accurate to within a few degrees, but generally, the more you pay, the better will be the result.
While it does not matter much where you install a barometer, inside or outside, it is vital your thermometer is not close to anything which might prevent the free flow of air or provide a heat or radiation source. For this reason it should be permanently in the shade, but not in a wind tunnel or cool corner. It should be about a metre above a grass surface. A garden thermometer stuck in with the tomato plants will tell you how hot it is among the tomatoes, but nothing else.
Generally an unshielded thermometer should be placed on the south side of a house because this will often be more likely to be in the shade and not be subject to radiation from the hot north-facing walls. A radiation shield of some type is important for an accurate result, either a commercially-available one (about $100) or even a white, wooden box with louvre slats.
What about under the eaves of a south-facing wall? Often this will end up being the home of the thermometer or electronic temperature sensor.
Just remember – it will only tell you what the temperature is where it is located, so if the official high temperature for Geelong is 38.5º and your thermometer shows 41º there are four possibilities:
- Yours may not be located properly to accurately measure the air temperature, or,
- Yours may be located correctly but be an inaccurate gauge one, or,
- There may be a difference between the air temperature at your location compared to the Bureau’s location at the Mt Duneed airport,
- Or a combination of all the above.