Most drivers rely on their car thermometer to adjust their speed, but the temperature indicated is not necessarily accurate.
The car thermometer basically allows you to know and monitor the outside temperature while driving. Information that is intended to be crucial for road safety. In fact, in winter, this helps to anticipate frost on the road, thus reducing the risk of skidding and possible collisions or accidents. In summer, this also allows you to know if the heat could affect the performance of the vehicle, particularly the engine. Concretely, the car thermometer gives important information to adapt your driving according to weather conditions, and thus avoid potentially dangerous situations.
But this tool is not really a classic thermometer as you might imagine. In reality, and as explained by the American weather channel The Weather Channel, the outside temperature displayed on your dashboard when you are driving “comes from a thermistor, not a thermometer.” On a classic thermometer, the temperature is measured using mercury. This blue liquid, contained in the thermometer, expands and increases when it is hot, and vice versa when it is cold. A thermistor, on the other hand, is a small component that changes its electrical resistance depending on temperature. It is used to measure or regulate the temperature in different devices, such as heating systems or electronic devices.
Most of the time, vehicle manufacturers place the thermistor in the front bumper, behind the air vents. However, at this location, the thermistor mainly measures the temperature emanating from the ground. In summer, but also in winter, roads, like any tarmac surface, absorb more of the sun’s rays. The thermistor then records the highest temperature of the roadway. This can dangerously distort drivers’ vigilance if they think that the road is just wet and they see, for example, a temperature of 5°, when in reality the road is completely icy.
The temperature indicated by your car thermometer can exceed the actual air temperature by more than 10 degrees, experts report. The Weather Channel. This is why it is better not to rely on your vehicle’s thermometer in winter as in summer. Instead, use a conventional thermometer if you want to know how much it really is outside.