On 4/4/2023 2:32 PM, Scott Lurndal wrote:
> djheydt@kithrup.com (Dorothy J Heydt) writes:
>> In article <u0hhkq$3fomk$1@dont-email.me>,
>> Dimensional Traveler <dtravel@sonic.net> wrote:
>>> Not to mention how many more pedestrians get mowed down because drivers
>>> can't see to the front end of their hoods.... I had to drive on
>>> Interstate 5 in the California Central Valley once during a heavy fog.
>>> I was in the far right lane, emergency blinkers on, doing maybe 30 miles
>>> an hour because I could see more than 10 or 20 feet in front of me and
>>> had multiple tractor-trailer rigs go past me doing at least 60.
>>
>> (Hal Heydt)
>> One technique--if your nerves can take it--is to follow someone
>> else, regardless of how fast they're gooing. Just stay far
>> enough back that you *just* have solid visibility on their tail
>> lights. If said lights get suddenly brighter, move the shoulder
>> and hit the brakes.
>
> I once drove (in the 1980s) from Los Angeles to Las Vegas after
> dark, on a freshly paved stretch of unstriped blacktop, in a heavy
> downpour - followed the tail lights of the car ahead and
> hoped they stayed on the highway.

Reminded of an old joke about someone doing that on city streets. When
they ran into the rear of the leading vehicle they wanted to know why
the lead driver hadn't used his brakes. "I was pulling into my driveway."

--
I've done good in this world. Now I'm tired and just want to be a cranky
dirty old man.

Dorothy J Heydt wrote:

> In article <1d96eee4-5519-4e1b...@googlegroups.com>,
> Jack Bohn <jack....@gmail.com> wrote:
> >(I believe I've mentioned my brother has appointed me tech support for
> >the devices he gives our mom. I've had to rehearse her in the word
> >"notifications," as when her Echo Dot is non-responsive, with lights
> >chasing themselves around the rim, she has to ask it, "what are my
> >notifications?" to free it up. This is how I found out the National
> >Weather Service has something called a "Dense Fog Advisory," which is
> >about the stupidest alert I can think of to tie up our electronic
> >communications with!")

> (Hal Heydt)
> You've never driven in the California Central Valley in a Tule
> Fog. The conditions tend to produce chain reaction accidents
> with upwards of 100 vehcles involved.

Flatlander here. Our fog could be anywhere, and, if I'm in the middle of it, as far as I can tell, it's everywhere.
With a certain local that you can report on the existence or not of a hazard I can see some sense -- we have caution signs that say "Bridge freezes before road surface" that we leave up year-round.
It just seems strange to me to warn that there may be places where you can't see, the indication of it will be that you can't see.

--
-Jack

Jack Bohn <jack.bohn64@gmail.com> wrote:
> Dorothy J Heydt wrote:
>
>> In article <1d96eee4-5519-4e1b...@googlegroups.com>,
>> Jack Bohn <jack....@gmail.com> wrote:
>> >(I believe I've mentioned my brother has appointed me tech support for
>> >the devices he gives our mom. I've had to rehearse her in the word
>> >"notifications," as when her Echo Dot is non-responsive, with lights
>> >chasing themselves around the rim, she has to ask it, "what are my
>> >notifications?" to free it up. This is how I found out the National
>> >Weather Service has something called a "Dense Fog Advisory," which is
>> >about the stupidest alert I can think of to tie up our electronic
>> >communications with!")
>
>> (Hal Heydt)
>> You've never driven in the California Central Valley in a Tule
>> Fog. The conditions tend to produce chain reaction accidents
>> with upwards of 100 vehcles involved.
>
> Flatlander here. Our fog could be anywhere, and, if I'm in the middle of it, as far as I can tell, it's everywhere.
> With a certain local that you can report on the existence or not of a hazard I can see some sense -- we have caution signs that say "Bridge freezes before road surface" that we leave up year-round.
> It just seems strange to me to warn that there may be places where you can't see, the indication of it will be that you can't see.

Most advisories are meant to give advance notice so that you can do something
different...stay home, leave early, take a different route, etc.
For fog, if it normally takes me 30 minutes to get to work I might leave 15
minutes early. For apocalyptic snowfall (2 or more inches in the Dallas area)
or ice I'd stay home.

Robert
--
Robert K. Shull Email: rkshull at rosettacon dot com

On Wednesday, 5 April 2023 at 13:09:18 UTC+1, Jack Bohn wrote:
> Dorothy J Heydt wrote:
>
> > In article <1d96eee4-5519-4e1b...@googlegroups.com>,
> > Jack Bohn <jack....@gmail.com> wrote:
> > >(I believe I've mentioned my brother has appointed me tech support for
> > >the devices he gives our mom. I've had to rehearse her in the word
> > >"notifications," as when her Echo Dot is non-responsive, with lights
> > >chasing themselves around the rim, she has to ask it, "what are my
> > >notifications?" to free it up. This is how I found out the National
> > >Weather Service has something called a "Dense Fog Advisory," which is
> > >about the stupidest alert I can think of to tie up our electronic
> > >communications with!")
>
> > (Hal Heydt)
> > You've never driven in the California Central Valley in a Tule
> > Fog. The conditions tend to produce chain reaction accidents
> > with upwards of 100 vehcles involved.
> Flatlander here. Our fog could be anywhere, and, if I'm in the middle of it, as far as I can tell, it's everywhere.
> With a certain local that you can report on the existence or not of a hazard I can see some sense -- we have caution signs that say "Bridge freezes before road surface" that we leave up year-round.
> It just seems strange to me to warn that there may be places where you can't see, the indication of it will be that you can't see.

You can see, but not so far. So, drive slower.
Stop before you hit something is a normal part
of driving. In fog you get less time for it.

If you can't see the road - that is way too much fog.

On 2023-04-05, Robert Carnegie <rja.carnegie@excite.com> wrote:
> On Wednesday, 5 April 2023 at 13:09:18 UTC+1, Jack Bohn wrote:
>> Dorothy J Heydt wrote:
>>
>> > In article <1d96eee4-5519-4e1b...@googlegroups.com>,
>> > Jack Bohn <jack....@gmail.com> wrote:
>> > >(I believe I've mentioned my brother has appointed me tech support for
>> > >the devices he gives our mom. I've had to rehearse her in the word
>> > >"notifications," as when her Echo Dot is non-responsive, with lights
>> > >chasing themselves around the rim, she has to ask it, "what are my
>> > >notifications?" to free it up. This is how I found out the National
>> > >Weather Service has something called a "Dense Fog Advisory," which is
>> > >about the stupidest alert I can think of to tie up our electronic
>> > >communications with!")
>>
>> > (Hal Heydt)
>> > You've never driven in the California Central Valley in a Tule
>> > Fog. The conditions tend to produce chain reaction accidents
>> > with upwards of 100 vehcles involved.
>> Flatlander here. Our fog could be anywhere, and, if I'm in the middle of it, as far as I can tell, it's everywhere.
>> With a certain local that you can report on the existence or not of a hazard I can see some sense -- we have caution signs that say "Bridge freezes before road surface" that we leave up year-round.
>> It just seems strange to me to warn that there may be places where you can't see, the indication of it will be that you can't see.
>
> You can see, but not so far. So, drive slower.
> Stop before you hit something is a normal part
> of driving. In fog you get less time for it.
>
> If you can't see the road - that is way too much fog.

But what do you do when it's perfectly clear for you going 70 mph, and
then you ascend a bit further up the hill and can no longer see the road?
If you stop, you'll get rear-ended. You drive slowly and hope the cars
behind and ahead of you are going about the same speed.

This is a not uncommon occurrence on I-99 when going through the
mountains of northern Pennsylvania. There are permanent signs
warning of fog, and they try to put portable electronic signs for the
areas when the dense fog patches come out. But it's an
adventure when there are non-locals around!

Chris

On Monday, April 3, 2023 at 8:11:49 AM UTC-6, James Nicoll wrote:
> Five Ways to Justify Huge Rocks Smashing Into Earth (in Spite of
> Science)
>
> How to salvage a beloved stock science fiction plot from the cruel
> ravages of applied science.

I was very surprised to hear that we are now so scientifically advanced that
we don't have to worry about being hit by asteroids any more. I thought that
the engineering discipline of diverting incoming asteroids was still in its
infancy, and we could only divert an asteroid heading for Earth if we were
really lucky in sighting it long before the actual impact, so that the tiny changes
we are able to make in an asteroid's orbit would suffice.

And lots of other space disasters can happen that are beyond our power.

Remember the Carrington event? I've recently heard that something far
worse, a Miyaki event, comes from the depths of space rather than our
Sun, which we can do nothing to avoid. And there was the possibility of
Betelgeuse going nova, although that danger appears to have been
downgraded.

And a post here already referenced the recent news item of an ultramassive
black hole, turning the interstellar medium into new stars behind it, is sweeping
through distant space. Imagine if such a thing were to have a close encounter
with our Solar System - the Sun and its planets would, at the very least, be
flung out in all directions separately away from each other.

We are still very weak and fragile creatures, who could easily be doomed
by any of hundreds of possible chance interactions involving the great
energies and masses that are all about us. Our Milky Way is on a collision
course with the Andromeda Galaxy, so our days are numbered, even if _that_
number is a rather large one.

John Savard

On Tue, 04 Apr 2023 21:32:44 GMT, scott@slp53.sl.home (Scott Lurndal)
wrote:

>I once drove (in the 1980s) from Los Angeles to Las Vegas after
>dark, on a freshly paved stretch of unstriped blacktop, in a heavy
>downpour - followed the tail lights of the car ahead and
>hoped they stayed on the highway.

Back in the late 1960s my father did that through the Siskiyou
mountains in northern California snowstorm where visibility was
"somewhat limited"

In the end we got hot drinks at a truck stop and I don't recall what
happened from there.

The kicker was that despite his studded snow tires the CA highway
patrol was insisting on chains so he got one chain on (using a
coathanger to connect the two ends of the chains since the studded
tires had a larger circumference than the standard snow tires) and
after he got the first one told my mother he wasn't doing the other
one and mercifully got waved through by the patrolman.....

The things you remember from childhood!

On Tue, 4 Apr 2023 16:24:02 -0700, Dimensional Traveler
<dtravel@sonic.net> wrote:

>Reminded of an old joke about someone doing that on city streets. When
>they ran into the rear of the leading vehicle they wanted to know why
>the lead driver hadn't used his brakes. "I was pulling into my driveway."
>
I've heard the same joke about a driver in a London fog - back when I
was learning to drive.

Some nasty relative figured it would reassure me before my road test!

On 4 Apr 2023 21:45:04 GMT, Jaimie Vandenbergh
<jaimie@usually.sessile.org> wrote:

>On 4 Apr 2023 at 14:41:46 BST, "Jack Bohn" <jack.bohn64@gmail.com>
>wrote:
>>
>> (I believe I've mentioned my brother has appointed me tech support for the devices he gives our mom. I've had to rehearse her in the word "notifications," as when her Echo Dot is non-responsive, with lights chasing themselves around the rim, she has to ask it, "what are my notifications?" to free it up. This is how I found out the National Weather Service has something called a "Dense Fog Advisory," which is about the stupidest alert I can think of to tie up our electronic communications with!")
>
>We got Yellow Snow Warnings this winter. Naturally it meant "Snow
>warning, grade yellow" on a scale of no-warning/yellow/red. But I liked
>the phrasing and hope it was intentional.

Picture?

We had about 3' this winter and the neighbors dutifully shovelled
their driveways and sidewalks - and our dog did his best to make that
sign you saw actually true.

We only got rid of the last of our snow about 10 days ago...

On Monday, April 3, 2023 at 3:01:54 PM UTC-5, Jack Bohn wrote:
> Johnny1A wrote:
> >
> > I've always found the 'asteroid impactor as weapon' scenario improbable, not because it couldn't be done, but because it doesn't do anything that a nuke doesn't do more easily and cheaply, plus it takes longer.
> Well, unless you already have a mass driver on the Moon you could use.
>
> --
> -Jack

Yeah, you _can_ weaponize a mass driver. But it's trickier than Heinlein presented it to be. (Also, RAH deliberately or by mistake overestimated how much damage the chunks he uses in the famous story would do.)

The advantage of using a mass driver is a limitless supply of ammo, and reasonably prompt strike time. It's also, _depending on the technology_, easier to deflect one medium-sized asteroid than it is to stop dozens of smaller chunks from a mass driver installation. For ex, if the enemy has a single 1000 foot rock coming at you, if you knock it just slightly off course you're fine. It would take much more time and delta-V to deflect several dozen small chunks on slightly different paths. OTOH, if you've got a big high power laser available and it has good enough focus, you could probably vaporize or deflect the oncoming rocks with it, because they'll still time to arrive and you can lase the targets as fast as you can redirect your beam..

(Even if it would take too long to entirely vaporize each rock, such a laser might still knock them safely off-course by inducing outgassing and the like.)

A mass driver would be a weapon potentially useful against fixed targets, but anything mobile could probably get out of the target zone easily in the time it would take for the projectile to arrive. Even foot traffic could probably do it, if they had warning at launch (which is likely given radar).

Also, a weaponized mass driver is itself very vulnerable. Break the track anywhere along the length and it's out of action. A successful use of a Lunar mass driver as a weapon probably requires either sufficient spae control that nobody can get close enough to hit it, or burying the whole thing underground or something (except for the launch opening, of course).

It's doable, yes. It might someday be done. But for it to actually _make sense_ requires specific conditions.