Behind the Science: Car Thermometers

 Is your Car Thermometer Right? During the last few weeks car thermometers have been reading over 100° in many cases with the extreme heat we had. Is that truly correct or is the thermometer on your car wrong? 

Correct Answer: The thermometer on your car is WRONG. Why?

Behind the Science: First, everyone knows we record temperatures with a thermometer. Gabriel Fahrenheit created the thermometer. The first ones used alcohol, later he used mercury. Mercury expands or contracts based on the temperature. 

Your car does not have a thermometer on it, it has a Thermistor! A thermistor uses electrical current to measure the temperature. Now these are both very accurate ways to record the temperature. The big thing is WHERE is exactly your car is that is it trying to record the temperature. These are off by a long-shot. 

Why is my car Temperature Wrong? Well, official weather stations are usually at an airport. They are in shaded areas, typically grassy areas that are in a controlled environment. In some cases, the thermometers are in a "Stevenson Screen" is has well-ventilated area, has air circulating through it and it is covered. You drive your car on paved roads, asphalt, concrete absorbs a large amount of heat increasing near the ground temperature. For example if the asphalt is 140°, your car will tell you it is 110° outside. WRONG!! The Thermistor is typically on your bumper on the driver's side of the vehicle. 

So that is "Behind the Science" with regarding your car thermometers! 

Student Meteorologist Brodie Wesson