A temperature of 46°C indicated on the dashboard of your car, while the outside temperature is only 34°C? In these times of extreme heat, the temperature given by your vehicle is often much higher than reality, as explained by the American media Quartz.
First of all, you should know that the car thermometer is not really a thermometer. Your vehicle uses a thermistor, i.e. a small electrical resistor that calculates the temperature based on different variations of electrical currents; this is the same process for digital thermometers that can be used to measure body temperature. In contrast, a classic thermometer refers to variations of mercury to give the temperature.
Biased data
But the problem is not the thermistors themselves, but rather their location in the car that needs to be taken into account. Manufacturers usually place these resistors at the front of the car, behind the grille. At this location, the thermistors measure the temperature close to the ground, explains The Weather Channel. However, the temperature above the road, heated by the sun, is higher than the actual air temperature, because roads absorb solar radiation and heat up quickly. The data displayed is therefore biased.
This explains why the difference between the temperature indicated by the car and the outside temperature can reach up to 12°C, especially for a vehicle parked in direct sunlight. But you should also be careful in winter: if the dashboard indicates 3°C, the outside temperature is probably actually negative.
Source: BFM TV
