Impact Winter - Writers Forum

Sam · 11-15-2004, 10:15 AM

Hey, I'm (re)starting a fantasy/sci-fi story which is set in a world which has previously suffered a asteroid impact. I have a bit of basic information on the possible effects of such a cataclysm, but what I really want to know is how long the dust kicked up by the impact would remain in the atmosphere before it settled? Are we talking centuries, years or hours? Also, how does it settle? Does the cloud as a whole lose density, or does it simply 'lower' to ground level, gradually exposing mountain peaks etcetera?

For the purposes of my story I'd prefer it to be a fairly long period before the dust settled, but I'd prefer it to be loosely based in science than not. In other words, I can just throw in some unknown reason for the extended duration of the cloud. It doesn't really need to be scientific, I just think it adds a little depth to the story.

Any other imformation on possible consequences of a giant asteroid impact are also welcome.

mammamaia · 11-15-2004, 11:44 AM

sam...
there are numerous novels and movies based on this premise, so in addition to googling for scientific info on the phenom, you might want to check out the myriad ways other writers have tackled it...

being a great lover of post-apocalyptic fiction, i've read/seen many of the works already out there, but can't really give you a list of titles off the top of my head, sorry to say...

best of luck with your project... have fun!

love and hugs, maia

Spudley · 11-15-2004, 12:00 PM

It would depend on different factors.

Obviously the size of the object would be important. Also where the impact occurs - on land or water (you won't get dust from an ocean impact unless it's truly huge, but you will get giant tidal waves), and at what latitude (global air currents and circulation are complex but would make a big difference to how quickly a dust cloud would spread).

Quote:

Does the cloud as a whole lose density, or does it simply 'lower' to ground level, gradually exposing mountain peaks etcetera?

The dust wouldn't be thick enough on a global scale to do that, even from a massive impact. To start with it would form clouds near the event, but it would quickly disperse and would be more like smog in that the atmosphere would become hazy. But unlike smog, it would be at all levels of the atmosphere rather than just at ground level. The cumulative effect would be that the sun would be a lot dimmer, and the days colder. But the sunsets would be awesome.

Something that might interest you:

Although written records from the period are sketchy, research into tree ring dating has revealed a long period of extremely poor growth around the mid-600s AD, and there is some evidence that this might have been caused by an asteroid impact in Africa. The data is only available for Europe, of course, since timbers that ancient aren't readily available in other regions, which means that the global effects aren't known for sure. You may want to do a bit more research on this topic.

Another topic you might want to look into is the effect of the Krakatoa eruption. This was the most violent volcanic eruption in recorded history, and caused "the year without a summer" in Europe (ie on the other side of the planet from the actual event). But there is evidence of much, much bigger eruptions in the geological record, which would surely have darkened the skies for decades.
(I know this last point is slightly off-topic, but the dust effects are very similar, and could help your research)

Czerez · 11-18-2004, 02:28 PM

Ever watch Armageddon or Deep Impact? Both are a little cheesy but they give good examples of large scale impacts...not visiually but im pretty sure they have scientists in the movies explain....

Are they completely correct, imnot sure. But movies are pretty good about it....at least most i have seen. Directors want you to believe that.

Sorry of topic i know. Uhm...Im almost positive a large impact..we are talking asteroid size of say..Cuba, Would wipe most living things out in a couple hundred mile radius. The shear air movement caused by an impact that size might throw off weather patterns and air currents.

Something that big would be like setting off a modern day Hydrogen bomb....or ten.

The dust would be up for a while. The amount of dust (and i know this is morbid) that came off the two towers when they fell was enough to gag and hurt quite a few people. We're only talking a few thousound tons at most there. And was at most only at terminal velocity speeds.

If an steroid was moving fast enough or had enough mass it could concevable throw a planet form orbit. So yea dust and dirt would be up for a while. Also depends on gravity. takes the moon months and years for dust that we kicked up to settle.

hope i got your mind working. Im not 100% positive on this stuff, but im pretty sure.

Spudley · 11-18-2004, 03:44 PM

Quote:

Originally Posted by Czerez

Im almost positive a large impact..we are talking asteroid size of say..Cuba, Would wipe most living things out in a couple hundred mile radius. The shear air movement caused by an impact that size might throw off weather patterns and air currents.

Something that big would be like setting off a modern day Hydrogen bomb....or ten.

Yes. It would. Cuba is a BIG island, and an asteroid as big as that would be utterly devastating. An object that size would kill us all. (the one that is said to have killed the dinosaurs was only 10 or 20 kilometers in diameter).

(not sure why you picked Cuba, though - it's an odd shape, which makes comparisons with an asteroid difficult

)

However, even a much smaller object could cause a lot of damage. An asteroid of only fifty meters diameter can leave an impact crater over a kilometer wide, and of course, the effect would be pretty devestating much further away than that. Good examples of craters of this sort of scale are the Barringer crater in Arizona, or the Soutpan crater in South Africa. These events generated exposions in the range of 10 to 20 megatonnes, which for comparison is 500 to 1000 times bigger than the 20 kilotonne exposion that destroyed Hiroshima.

So given an accurate aim, an object the size of a large house could pretty much destroy a good sized city instanenously.

Spudley · 11-18-2004, 03:48 PM

By the way, Czerez... you might be interested in this:

Not sure if you know.... the name of the largest asteroid of them all is Ceres.

Czerez · 11-18-2004, 10:30 PM

i didn't know that thanks...hehe yay!....