Car mounted weather stations: pole length

[Andrea Griffa]

Hi all
Who knows how long has to be the pole of a car mounted weather station?

I mean, it's important that the radiation shield is not too close to the rooftop of the car, in order to not be influenced by the heat of the metal.
I made my pole 70cm long. What do you think about?

 

[David Wolfson]

Andrea, apart from the separate issue of how to mount an anemometer, which is more complicated, I'd venture that the vehicle's roof can be considered as "the ground". If you want to be scientifically correct, then I imagine you'd site the instruments at WMO standard height for a ground station, which I understand is 1.25m. FWIW.
http://weatherfaqs.org.uk/node/124

 

[Jason Foster]

It depends on how accurate your wanting your data. For me...for chasing purposes (NOT research purposes) than just a half a meter to one meter is plenty. Being from Italy I'm gonna 'assume' you rent a car, but for those that own, you can also paint the roof white to lessen the affects if you own a dark color car. I did this to my Dodge Caravan...and it really works (keeps the inside a bit cooler too).

 

[Sean Waugh]

you can also paint the roof white to lessen the affects if you own a dark color car.

This is actually quite a loaded statement as it not only depends on the color of the roof, but primarily on the thermal mass of the roof. If you have a black, solid metal roof then it's going to heat up considerably and re-radiate a lot of that heat upwards. If however, you roof is made of say, some sort of dent resistant plastic, then even a black roof won't heat up as much and therefore won't re-radiate that energy. Conversely, painting it white may have some negative affects. For example, you paint it white, which reflects a lot of the incoming solar radiation. Now that temperature shield that before was only getting the irradiance from the sun, is now getting the irrandiance from the sun AND the reflected irradiance from your car roof. The effective heating ability can go up considerably just by changing the car roof to white. So, the answer to this thread's question is far from simple.

 

[Jason Foster]

I think Saturn is the only car that has a plastic roof, and that was only on some models.

All I know is when I did it...the sensors where more accurate AND it was slightly cooler inside (according to the weather station).

 

[Andrea Griffa]

Thank you guys, nice observations