h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Surely you must have noticed? It's usually in the morning, but yesterday (yes, I know tonight is Bonfire night, but yesterday was the day after the nearest Saturday, which is just as bad if not worse), a deep and abiding fog descended around 4pm, made itself comfortable, and settled in for the evening.

During said evening I went from Bromsgrove to Malvern and back, and it was fog all the way.

I find that the days around Bonfire night are typically foggy ones. Anyone got any idea why this should be? Is it something to do with all the CO2 generated that night?


Geggs

My guess:
All the soot particles and particleites make the humidity in the air condense. So in addition to the smoke residues itself, humidity forms fog. Then there might be the chemicals of other types hangning about, acid springs to mind... again, a change in the normal environment, and presto, condensation.

What do you think?

That's the very reason my lecturer gave this morning . Increase in particulates onto which water vapour can condense.

I must have listened without noticing at some time or other!

Is it always foggy after bonfire night? I'm not convinced.

It wasn't foggy here this morning although it was yesterday morning.
Although one could say the majority of fireworks displays were probably held over the weekend this has the feel of anecdote and myth to me.

Is it not just that there is a general high chance of fog because is is November?

I think it's a bit of both.

Did you have lots of actual bonfires then?

Lots of 'actual' bonfires, yes. A few pretend ones too.

of course we have lots of real actual genuine bonfires. It's one of the only truly big British traditions apart from binge drinking that stays alive. Lots of people have small parties in their back garden but much bigger "fireworks" are put on by groups like the scouts (paramilitary children), the rotary club (fat masons) and churches (don't get me started!).

We even cover apples in toffee, eat the toffee and throw away the apple.

I made toffee plums.

And are you allowed bonfires in back yards in general, or is there a law that allows it on that night? Just curious, given all the 'UK strict nanny state' posts I see round here (hootoo, not SEx ).

I believe some areas have local by-laws against bonfires during the day (although that could just have been my mother going off on one, many years ago). Farmers and allotment holders seem to have bonfires when they feel like it. But households that wouldn't light a bonfire on any other night of the year will have one on 5th Nov, and there are a *lot* of big f-off bonfires at public events around that date.

Mol

Actually Birmingham is a "smoke-free" city which means we are not allowed fires at all in our gardens. It's important to remember (in my opinion) that we treat a lot of the laws here more like guidelines, which are useful for everybody else to follow.

They'll still sell you incinerators at Hardware stores though

Not that I found this out or anything

This thread has made an old insominac very happy. Thanks

It will not always be foggy after a bonfire night as it is not only due to the seeding effect of the chemicals from the fireworks in the air but also the humidity(water content) and temperature of the air as well. Therefore if it happens to be a crisp dry night with very low humidity the chances of the water condensing onto the particles in the air will below.

However, as November is obviously not the driest of months the probability that the humidity and temperature will be right for water condensing out and causing fog will be high.

It was very foggy when I got up this morning and I immediately remembered this thread!

'All the soot particles and particleites make the humidity in the air condense.'

Yes. There is a group of particles called PM10s ('articles Microparticulate <10 microns diameter'. These are so small that they penetrate deep into the lungs causing various pathologies. There is a 'nice ....'graph from the USA showing a direct correlation between PM10 concentration and death rate.

These particles increase dramatically in concentration during Bonfire Night.

http://www.aeat.co.uk/netcen/airqual/networks/faq/epimisc.html

Actually, Trig and I wrote a bit more about PM10s in A16407173.

A