Of course, there is no practical difference between radiation fog, hill fog or advection fog.

I would suggest that everyone is "used to" fog in that they have seen it before, although it is a more frequent occurrence at altitude in certain areas. And any driver encountering fog should react immediately anyway.

However, we know that many people do not, particularly on motorways. As such it could be argued that there is greater "impact" at lower levels, simply by dint of far greater volumes of fast-moving traffic. However, I am not arguing in favour of ignoring warnings for hill fog, and as Norman points out there are major roads at altitude. Indeed, the M62 reaches about 350m amsl at Saddleworth Moor (correct me if I'm wrong).

Stephen.

On Friday, November 13, 2015 at 2:35:09 PM UTC, Stephen Davenport wrote:
Of course, there is no practical difference between radiation fog, hill fog or advection fog.

I would suggest that everyone is "used to" fog in that they have seen it before, although it is a more frequent occurrence at altitude in certain areas. And any driver encountering fog should react immediately anyway.

Very true. Imagine someone being 'used' to fog on Dartmoor and not elsewhere! Bet Will is terribly unsure when he encounters fog on a motorway and I hope he's driving nowhere near me, as he'll clearly be very unused to the radiation fog found on lowland motorways, as he mainly gets hill fog on Dartmoor. laughing,

However, we know that many people do not, particularly on motorways. As such it could be argued that there is greater "impact" at lower levels, simply by dint of far greater volumes of fast-moving traffic. However, I am not arguing in favour of ignoring warnings for hill fog, and as Norman points out there are major roads at altitude. Indeed, the M62 reaches about 350m amsl at Saddleworth Moor (correct me if I'm wrong).

Stephen.

On Friday, November 13, 2015 at 10:55:51 AM UTC-5, Dawlish wrote:
On Friday, November 13, 2015 at 2:35:09 PM UTC, Stephen Davenport wrote:
Of course, there is no practical difference between radiation fog, hill fog or advection fog.

I would suggest that everyone is "used to" fog in that they have seen it before, although it is a more frequent occurrence at altitude in certain areas. And any driver encountering fog should react immediately anyway.

Very true. Imagine someone being 'used' to fog on Dartmoor and not elsewhere! Bet Will is terribly unsure when he encounters fog on a motorway and I hope he's driving nowhere near me, as he'll clearly be very unused to the radiation fog found on lowland motorways, as he mainly gets hill fog on Dartmoor. laughing,

However, we know that many people do not, particularly on motorways. As such it could be argued that there is greater "impact" at lower levels, simply by dint of far greater volumes of fast-moving traffic. However, I am not arguing in favour of ignoring warnings for hill fog, and as Norman points out there are major roads at altitude. Indeed, the M62 reaches about 350m amsl at Saddleworth Moor (correct me if I'm wrong).

Stephen.

========

You might have missed my point, or I did not state it carefully enough. It was not intended as a criticism of Will whatsoever.

Stephen.

On Friday, 13 November 2015 14:35:09 UTC, Stephen Davenport wrote:
Of course, there is no practical difference between radiation fog, hill fog or advection fog.

I would suggest that everyone is "used to" fog in that they have seen it before, although it is a more frequent occurrence at altitude in certain areas. And any driver encountering fog should react immediately anyway.

However, we know that many people do not, particularly on motorways. As such it could be argued that there is greater "impact" at lower levels, simply by dint of far greater volumes of fast-moving traffic. However, I am not arguing in favour of ignoring warnings for hill fog, and as Norman points out there are major roads at altitude. Indeed, the M62 reaches about 350m amsl at Saddleworth Moor (correct me if I'm wrong).

Stephen.

Not sure I agree with your first point. Radiation fog can be very patchy and at motorway speeds you can run into it very suddenly. When you run out of it you naturally speed up, thinking there'll be no more fog and then you run into another patch. Hill fog, on the other hand, tends to be much more uniform and when you descend out of it you know that's the end of it.

On Friday, November 13, 2015 at 12:26:58 PM UTC-5, Tudor Hughes wrote:
On Friday, 13 November 2015 14:35:09 UTC, Stephen Davenport wrote:
Of course, there is no practical difference between radiation fog, hill fog or advection fog.

I would suggest that everyone is "used to" fog in that they have seen it before, although it is a more frequent occurrence at altitude in certain areas. And any driver encountering fog should react immediately anyway.

However, we know that many people do not, particularly on motorways. As such it could be argued that there is greater "impact" at lower levels, simply by dint of far greater volumes of fast-moving traffic. However, I am not arguing in favour of ignoring warnings for hill fog, and as Norman points out there are major roads at altitude. Indeed, the M62 reaches about 350m amsl at Saddleworth Moor (correct me if I'm wrong).

Stephen.

Not sure I agree with your first point. Radiation fog can be very patchy and at motorway speeds you can run into it very suddenly. When you run out of it you naturally speed up, thinking there'll be no more fog and then you run into another patch. Hill fog, on the other hand, tends to be much more uniform and when you descend out of it you know that's the end of it.

=================

I simply meant that for practical purposes it reduces visibility when you drive into it. Of course there are nuances.

Nevertheless you can still drive in and out of hill fog with slight chances in cloud base or altitude, or maybe if you get lee side. You might be fooled into thinking you are out of it when you're not.

Stephen.