Why a car thermometer doesn't always show correctly

Undoubtedly, you had to sit in the car on a hot summer day, turn the key and see the temperature on the devices, which is clearly higher than the real one. Meteorologist Greg Porter explains why this is happening.

The car measures the temperature with a so-called "thermistor" - similar to a thermometer, but instead of a bar of mercury or alcohol, it uses electricity to read the changes. In fact, temperature is a measure of how fast molecules move through the air - in warm weather, their speed is higher, Porter recalls.

The problem is that in 90% of cars, the thermistor is installed right behind the radiator grill. In summer, when the asphalt heats up well above the ambient temperature, the car will take this difference into account as well. It's a bit like measuring the temperature in a room by placing a thermometer a foot away from a burning fireplace.

Serious measurement differences are most apparent when the vehicle is parked. When driving at higher speeds, the sensor detects much less heat generated by the asphalt. And in normal or cold weather, its readings largely coincide with real temperatures.

However, Parker warns that one should not blindly trust the readings, even in winter - especially when a difference of one or two degrees can mean the danger of icing.