Quantifying Fog
 

Anyone know any methods or specialist instruments for quantifying fog - particularly particle size & density? A self-contained, air vehicle-mounted solution with, preferably, digital output to a data system would be preferable.
Thanks,

We should talk on Monday morning!!! What on earth are they trying to do now? Presumably its for the EVS?

I think the device you are looking for is a transmissometer. It measures the amount of light that is refracted by water or particulates and, if you have a calibration, you can thence estimate denisty of the particulate etc.

By definition - fog is low lying so why would we need something on the air vehichle? To measure the benefit of peering through it I assume?

Would it not be sufficient to use the RVR measuring systems on the field? maybe it would be worth talking the folks that run the NOAA station on Tyler just south of our happy place of work!

There are various fog models that are used for instrument approach lighting and simulators.
Don't know where to find out more details, but some of the chaps at Bedford or the CAA might be able to help.

Thanks, Shawn, but I'm looking for input on an active sensor not a model. Your guess was a good one though. Found a device called "SID" (Small Ice Detector) on the U. of Hertfordshire site with a picture of it mounted on what looks like the Boscombe Down Weather C-130. Was hoping someone who had experience with it or similar systems could give me some guidance.

Measuring fog
 

ICT_SLB,

I believe the device you need is called a Nephelometer ( at least is is here in the UK - it may be that the Transmissometer mentioned earlier is correct in the US). Either way, these things look at the transmission medium ( air) by measuring the back scatter from a light source ( usually a laser) . Typical application is the side of the motorway.

I suggest you try Vaisala Ltd in Suffolk (UK) on 01638 576200, they do models with RS 232 or 485 output direct to a lap top or PC.

Good Luck

Edna C

ICT_SLB
The Weather Herc at EGDM is no longer operated in that mode, politics! :(
Yes we did have several instruments on board that could have measured the parameters you mentioned. The SID mentioned above was designed to measure Small Ice Particles, so no use to you. Of more use would be possibly one of several optical array probes manufactured by PMS Inc in the states, and are common for airborne atmospheric research world wide.
At the moment the Met Office don't have a research aircraft. They are still awaiting BAESystems to deliver the BAe-146-300 to the UK Universities(About a year late so far and counting.....) :rolleyes:
The MEt Office will then be subcontracted to operate the aircraft (from the science point of view) for the universites.

However, the Met Office cloud physics/aerosol specialists who flew on the weather Herc (Snoopy to her fans) still exist at the Met Research Flight at Farnborough. Try phoning the Met Office (++ 0845 300 0300) and ask to speak to one of these specialists. We used to fly a combination of instruments to measure the sort of things I think you want.

Good luck.