Parameters like that can predict that fog is likely, but to actually identify fog you need to observe that the visibility is less than 1 km. (Visibility between 1 and 5 km is haze or mist.) The automated weather observation systems commonly installed at airports and other locations include a visibility sensor that measures how much light is scattered in a small volume of air. The principle is pretty simple but I haven’t seen any low-cost consumer version.
-Les > On 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. -- 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/9F5E54C4-1CE2-434C-AAC0-95474D4E9A34%402pi.org.
