How is temperature measured?

Have you ever wondered why your garden or car thermometer often reads differently from the forecast temperatures?

Often your thermometers will be exposed to sunshine for lengthy periods during the day.

That causes the mercury to shoot up. But what is actually happening is the sun is warming up the surface of the thermometer, which gives a reading of the thermometer temperature rather than the air temperature.

In order to be able to compare temperatures, we need to ensure they are all measured in a consistent way in a standardised environment. This is done universally using a Stevenson Screen and the set-up is the same around the world.

You may have seen these dotted around - they look rather like a beehive from the outside.

These screens stand at a certain height above the ground, are painted white, and are slatted to allow the free passage of air.

The thermometer, along with other meteorological instruments, are kept inside, in the shade.

Posted By: Chris Peacock, Jul 19, 13:47:58