Car outside temperature indicators

[The Tiggster]

How do they work?

1. where are they generally located?


2. how do they take into account the wind chill from travelling & the heat from sitting in the shade?

Thanks!

[Toureman]

The temperature gauge itself is of coures on the dash of the car, The sender unit (this sends the tempature readings to the gauge) is located behind the front bumper where it is in the shade and also protected from the wind,

The gauge is very rarely perfectly accurate,after a long drive the gauge will read high as it picks up heat from the engine when stationary. When the car is being driven fast the wind will affect it slightly.

[Clanad]

Toureman sounds quite authoritative and I certainly wouldn't dispute anything said except, I would question any affect on the temperature by wind passing over the sensor/sending unit. It's somewhat like determining wind chill... it really is only noticeable on bare skin. A thermometer will read only the air temperature, regardless of wind, unless one dampens the thermometer. So, assuming the sensor is dry, no change would be noted whether the car is moving or parked... In my opinion...

[buildersmate]

Clanad, I reckon you are spot on. Wind chill relates to the human body's reaction to the actual temperature - not the temperature itself. Heat is lost from the skin to the cold air. If there's no movement of that air, the air is warmed slightly but remains close to the skin. If its constantly being replaced by more cold air because a wind is blowing, the skin is constantly being exposed to air at the cold (base) temperature. Forecasters produce this analogy of wind chill factor to help us appreciate moving air at a fixed temperature is like sitting in still air at a much colder temperature.

[gammaray]

If all that is true clanand how to they tell what the wind chill temperature is? Surely they don't strip a weather person and strap temperature sensors to their skin and push them outside on a cold and windy day?

[qapmoc]

Hi gammaray, Clanad and buildersmate are correct, The wind chill is calculated from the heat generated by an average person and the average heat loss which would occur at any particular wind speed, Nasa have anticipated your question and have info here on this subject.

[boink]

just to add, some cars have the "sender unit" as toureman called it in the wing mirror, usually looks like a drip coming from the bottom

[nijaxx]

If the sensor has very little temperature rise( due to any electrical power dissipation, and its thermal resistance), it will not get much colder when the wind blows. But I like gammaray's blueness test.

[The Tiggster]

Thank you to everyone who contributed & raised a few questions on the subject - very interesting. I will never look at the gauge in my car in the same way again