I find it hard to beloved they are all wrong.
Originally Posted by: Darren S
No need to get all emotional about it
It's always been the way of 'official' temperatures. The data recorded by the Met Office for records, etc has to be manually read on standard mercury max/min and wet/dry thermometers (someone correct me if this is no longer the case). This obviously requires people to get out there at regular intervals, which is fine for Heathrow and Kew and Wisley, etc, but not for all locations.
We all like to think our own garden instruments are providing accurate readings but without any scientific or repeatable verification you can never be sure. And if they are not in a decent shaded spot, preferably in a screen preventing wind anomolies, then it's just for fun . . .?
Originally Posted by: nsrobins
Exactly. The easiest thing in the world is to record a temperature that is too high on a hot day. That's because as the sun shines on things like buildings, they absorb the heat and then radiate it out. Couple that with light being reflected off glass and shining on other objects, and obstructions like buildings and trees preventing proper air movement, there's lots of things that can affect the temperature.
Most people don't have huge gardens, and put their weather stations in places which could be affected by any of these issues. So whilst you might be accurately recording the temperature in your garden, next door's garden will be different, and other houses different again; in fact different parts of your garden will have different temperatures. Therefore, such readings have no value in accurate national comparison, any more than Jiries' shed thermometer does.
Officially sited thermometers should be away from such obstructions and heat-absorbing surfaces so that the temperature is representative of that locality. Heathrow is a moot point I guess, but rather than recording an incorrect temperature due to a building a few metres away, it is recording the temperature of the whole locality. Yes, there is lots of tarmac and aircraft engines, etc. around Heathrow, but the temperature there is probably representative of the whole airfield (an area of several square miles) so therefore it is valid - unless we pretend that a huge area of the country that is built on doesn't exist.
Originally Posted by: picturesareme