Motoring Discussion > Fog Lights Again Miscellaneous
Thread Author: Robin O'Reliant Replies: 12
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New Fri 20 Mar 15 10:14 
 Fog Lights Again - Robin O'Reliant
Driving into work just before 7 this morning with a very heavy mist and visibility down to less than 50 metres in places. Of the oncoming traffic along my two miles of the A40 not a single car had fog lights on, about a third were trusting to sidelights and one had no lights at all. Quite a contrast to when it gets dusk and every other car seems to be using front fogs.

Strange thing, your human being.
Last edited by: Robin O'Reliant on Fri 20 Mar 15 at 10:15
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New Fri 20 Mar 15 10:40 
 Fog Lights Again - VxFan
Can't see the point of front fog lights on in daylight. Headlights alone are enough to make you visible in fog. Front fogs only come into play at night to cut underneath the fog to help improve being able to see the road in front of you.

In short, front fogs are there to help the driver see where he's going, not for others to see you.

Plenty of cars on the road without front fogs fitted that are visible enough providing their headlights are on dipped beam.
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New Fri 20 Mar 15 10:42 
 Fog Lights Again - Bromptonaut
More or less what Vx said. Dipped mains should be sufficient in daytime fog - plenty cannot manage that though.
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New Fri 20 Mar 15 11:06 
 Fog Lights Again - Slidingpillar
Driving into work just before 7 this morning with a very heavy mist and visibility down to less than 50 metres in places.

So foggy then. Meteorologically visibility less than 1000 yards, fog; more than 1000 yards, mist, or at least that what they said when I was at school.
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New Fri 20 Mar 15 11:16 
 Fog Lights Again - WillDeBeest
1000 or 100? 1000 is a fair old way. Haven't looked it up, mind. Fact are overrated.
};---)

Late thought: the Shipping Forecast also uses 'smoke' and, I think, 'haze' for lighter degrees of murk.
Last edited by: WillDeBeest on Fri 20 Mar 15 at 11:17
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New Fri 20 Mar 15 11:48 
 Fog Lights Again - WillDeBeest
Here we are:
www.metoffice.gov.uk/media/pdf/f/c/Fact_sheet_No._3.pdf

1,000m it is, but that's for 'aviation fog'; 'thick fog' starts at 200m and 'dense fog' at 50m.
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New Fri 20 Mar 15 14:24 
 Fog Lights Again - Slidingpillar
Ahh, usual school-teacher disease then, complicated issue - so simplify it, and then pass the results off as the truth.

I'm still annoyed with teacher who said pi was 22/7. Presumably the teacher assumed the concept of an approximation could not be handled by small brains.
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New Fri 20 Mar 15 14:32 
 Fog Lights Again - Armel Coussine
>> I'm still annoyed with teacher who said pi was 22/7. Presumably the teacher assumed the concept of an approximation could not be handled by small brains.

Surely not SP. The teacher was giving the real value of pi. Small brains can certainly understand that 3.14159etc. is a closer approximation than 3.142, and in the process learn that some numbers are always approximations, although the approximation can be made as it were infinitely close to the real number... the endless recurrence is interesting in itself. It was to my small brain anyway.
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New Fri 20 Mar 15 14:55 
 Fog Lights Again - Slidingpillar
22/7 is a rational number, pi isn't.

There are a number of ways the issue could have been correctly handled and the teacher would not have questioned, if that was the fear.
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New Fri 20 Mar 15 16:46 
 Fog Lights Again - Cliff Pope

>>
>> Surely not SP. The teacher was giving the real value of pi.

22/7 isn't the real value of pi. it's just a handy approximation, good enough for answering questions about bicycle wheel diameters and distance travelled.


There's a theory that the ancient Egyptians either didn't realise that pi was not 3, or else decided it was good enough when measuring distances using a wheeled device for marking out pyramids, so explaining the odd but consistent angle they used for the slope.
The theory may have been debunked now.
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New Fri 20 Mar 15 21:59 
 Fog Lights Again - Slidingpillar
There's a theory that the ancient Egyptians either didn't realise that pi was not 3, or else decided it was good enough when measuring distances using a wheeled device for marking out pyramids, so explaining the odd but consistent angle they used for the slope.

My money is on they were quite aware pi was not 3, but their number system which didn't have a decimal point could not really cope. They could have settled on 22/7 as the system could have coped (almost) with 3 and 1/7th, but quite how one would do calculations with their number system is another matter.
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New Sat 21 Mar 15 09:04 
 Fog Lights Again - Shiny
I suppose when it's foggy no-one can see those cool 'me-too' lights so what's the point in turning them on.
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New Sat 21 Mar 15 09:07 
 Fog Lights Again - Boxsterboy
I haven't the foggiest what you're on about :-)
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