I think you need a way to measure light attenuation between two points. Around here, (SF Bay Area), summer fog comes with cold dry wind off the ocean/bay mixing with warm damp air over land. It's fog on the hill tops and low clouds elsewhere. Winter fog (tule fog) is extremely patchy with conditions essentially identical at one spot where it's very foggy and another a mile away where it's clear. Not sure which kind of fog you're trying to detect.
In either case I think you need something that actually detects the change in visibility. I think a light source and a detector a meter or two away would do it. On Fri, Sep 3, 2021 at 6:06 AM František Slimařík <[email protected]> wrote: > Hi, > > just like I mentioned in the start, it will not be so easy to predict fog. > In case of my location I had following conditions this morning between > 5-6AM and no fog was visible. Just condensation on the cars etc. > > Temperature between 6-7°C > Humidity 97% > no wind > no solar radiation > also difference between temperature and dew point was just 0,4°C > > Dne pátek 3. září 2021 v 13:51:16 UTC+2 uživatel mihec napsal: > >> I'm using Weather Display with one of my stations and use the built in >> function to set the fog/haze conditions. It works very good. >> Fog conditions: >> * T < 10°C >> * 95% >= humidity >> * low wind or no wind >> * solar radiation low >> >> Haze: >> * T < 13°C >> * 94% >= humidity >> * low wind, low solar >> >> I might have slightly adapted humidity threshold, I don't remember. >> >> >> sreda, 01. september 2021 ob 00:29:22 UTC+2 je oseba [email protected] >> napisala: >> >>> In general, the possibility of fog developing is when the dewpoint >>> spread is less then 5 degrees F. >>> >>> On Tuesday, August 31, 2021 at 6:02:58 PM UTC-4 [email protected] wrote: >>> >>>> * On 2021 31 Aug 14:35 -0500, František Slimařík wrote: >>>> > >>>> > Hi all, >>>> > >>>> > I got question for hardcore meteorologists here. Is it possible to >>>> detect >>>> > fog based on classic meassured values like temperature, humidity, >>>> preasure, >>>> > etc? >>>> > Logically I would say fog appears when dew point equals current >>>> > temeperature but I guess it will not be so easy. Fogs didn't appear >>>> here >>>> > this year in my locality so I am waiting for autumn to start with >>>> > observations. >>>> >>>> I'm certainly no meteorologist! >>>> >>>> It seems we've had more foggy mornings this summer than in years past. >>>> Humidity has certainly been high with only a handful of stretches with >>>> more than a day below 50% relative humidity. >>>> >>>> Many times it seems as though warm air over cooler moist ground is >>>> necessary for its formation. I don't think this is a temperature >>>> inversion, as such, but they also seem to sometimes be quite localized >>>> and are related to some interesting effects. >>>> >>>> I along with other radio amateurs and possibly Greg find the effects of >>>> these weather phenomena on VHF and UHF radio propagation interesting. >>>> >>>> - Nate >>>> >>>> -- >>>> "The optimist proclaims that we live in the best of all >>>> possible worlds. The pessimist fears this is true." >>>> Web: https://www.n0nb.us >>>> Projects: https://github.com/N0NB >>>> GPG fingerprint: 82D6 4F6B 0E67 CD41 F689 BBA6 FB2C 5130 D55A 8819 >>>> >>>> -- > You received this message because you are subscribed to the Google Groups > "weewx-user" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/weewx-user/909cb30b-7281-4d27-99eb-59b0f3dfb41dn%40googlegroups.com > <https://groups.google.com/d/msgid/weewx-user/909cb30b-7281-4d27-99eb-59b0f3dfb41dn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- Peter Quinn (415)794-2264 -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/CAA1SM22KNXokhwsnVeo5QrmqkgTkjSaRL%3DmoFEYY%3D79F%2BDRS%3Dg%40mail.gmail.com.
