GREENSBORO, NC – Whew! It. Is. Hot. But HOW hot is it?
The car thermometer says 83°. But can we trust those thermometers?
Weather.com says no. First of all, the item in your car is as a thermistor - not a thermometer. Here’s the difference:
temperature, measured by a thermometer, is usually measured with a mercury thermometer which expands and rises when heat is added and contracts when it falls.
A hermistor measures the change in electric current when heat is added or removed. Thermistors are usually accurate so that's not really the problem.
But Weather.com says the real problem is the thermistor's location.
Most automakers put it on the front of the car behind the grill - but that exposes it to heat from the road. So it's basically recording the temperature over the road which can be hotter from the sun.