7 degrees in 3 miles

rainbowdash

I was in my garden this afternoon tipping around fixing a few bits blown around in the recent winds. It was a bright clear day with a hint of heat from the Sun. I hopped into my car and the temp was +6.

10 minutes and 3 miles later and was in thick fog and the temperatue was -1 and it was freezing when I got to my destination 3miles away.

I've never know my car thermometer to swing so quickly.

Pangea

It takes a while for the car thermometer to get accurate in my opinion, I think it works better when the cars been running a while. Maybe thats why the significant change?

Your car thermometer was not reading the correct temp when it was in your drive.
That often happens with some car thermo's-they tend to rise when parked and then pick up the ambient proper temp after a few minutes on the road.

You may have never noticed a 7 degree varience before because for whatever reason,there may never have been.
For instance , the real temp at your location could have been 4 degree's and then you hit the freezing fog.The mis reading accounting for the extra drop.
But I'm pretty sure thats the probable explanation.

rainbowdash

Even allowing for the thermo to be a bit off there was a hint of heat from the Sun and a few minutes later it was bloody cold.

Mothman

Its plain to see where the sun got to today. Most of the snow thawed, in shade no thaw even on velux window with 17C inside, it did not thaw!

In many vehicles, the thermometer is in the mirror. If the sun is shining on mirror then it'll will warm up and it takes time to cool.

Even a 7C difference is very plausible in a much shorter distance

Deep Easterly

Other car themos are placed inside the front or back bumper which is quite close to the ground. Temps at that level tend to fall much quite than standard height so that could be it.

Danno

Car thermometers are quite inaccurate IMHO.