Cloud seeding and firefighting

[hagopbul]

TL;DR

A question about atmospheric physics and its application

Hello:

Heard in the news that there is massive fire disaster in los angeles , california

And a question came to me , what about cloud seeding isn't it a possible method to help handling this disaster

How much time will take from cloud seeding start date until it start to rain on the fire zone

How wind will effect the operation

Is it valuable method on the scale of the resources that it requires

Best regards
H

 

[Dale]

Cloud seeding has never been shown to be effective

 

[hagopbul]

In dubai they did a mistake resulted in a lot of rain on entire city of dubai , would that accident help in creating a similar condition over the fire zone , taking into account the above questions

 

[Motore]

In dubai they did a mistake resulted in a lot of rain on entire city of dubai , would that accident help in creating a similar condition over the fire zone , taking into account the above questions

The rain in UAE was not because of cloud seeding.
https://en.wikipedia.org/wiki/2024_United_Arab_Emirates_floods#Cause

 

[DaveE]

Well... You'd need clouds first.
The warm, dry, Santa Ana winds from the desert are the problem. If they had clouds hanging around, they wouldn't need to seed them.

 

[hagopbul]

Could smoke shells for example the ones used by the artillery reduce the concentration of oxygen in the fire zone or making it harder for fire to spread reducing its spreading and easing its extinguish? Is there possibility of harming people nearby, or make it harder to rescue people ?

 

[jbriggs444]

Could smoke shells for example the ones used by the artillery reduce the concentration of oxygen in the fire zone or making it harder for fire to spread reducing its spreading and easing its extinguish? Is there possibility of harming people nearby, or make it harder to rescue people ?

Apparently, depleting oxygen from the normal 21% to about 15% is enough to prevent fires from starting. This is not a viable idea for fighting wild fires, however.

It would take an extremely large supply of ordinance. Try calculating how much oxygen there is in one square mile of atmosphere up to a height of 100 feet. I get about 42 million pounds. Even if we only have to deplete about 1/3 of that, that's still 14 million pounds per square mile.

Then in any sort of wind, the beneficial effect would be blown downwind. You would have only a few minutes before your one square mile of depleted atmosphere would be one mile downwind. And stirred up to a height of 200 feet.

We already have aircraft flying, delivering actual fire retardant chemicals. Having them drop smoke bombs instead would be rather silly.

Let's do a back of the envelope calculation for heat production...

Normal air is about one ounce per cubic foot (handy number to memorize). If we have a one square foot column, 100 feet in height, that's about 78 ounces of nitrogen, 21 ounces of oxygen and one ounce of everything else. We want to deplete six ounces of that oxygen, reducing it to 15 ounces in our square foot.

Coal is about 12,000 BTU per pound. 12 units of coal (C) will turn 32 units of oxygen (O2) into carbon dioxide (CO2). We have only 6 ounces of oxygen, so we'll need only 2.25 ounces of coal. That amounts to about 1600 BTU. That is enough heat to raise one pound of water by 1600 degrees Fahrenheit.

We are going to end up with a pretty toasty square mile of real estate. If it was not on fire before, it will certainly be blazing afterward.


Generally speaking, the guys working at specialized professions such as fire fighting are pretty good at what they do.

 

[Dale]

Also, you would need to maintain the low-oxygen environment long enough for the burning material to cool off below the (re) ignition temperature. That is one reason that water is so useful. It deprives the fire of oxygen, and it also removes a lot of heat.

It would be hard to use any method to remove the oxygen for long enough to prevent reignition without also killing any animals or humans in the area. Most animals and humans can survive a good accidental soaking better than an accidental asphyxiation.

 

[Baluncore]

TL;DR Summary: A question about atmospheric physics and its application

How much time will take from cloud seeding start date until it start to rain on the fire zone

Cloud seeding must be done about one hundred km up-wind of the target for the rainfall. It can only trigger an earlier precipitation from clouds, precipitation that would have fallen anyway, somewhere else over the next few days.

If the air below the rain cloud is warmer, or has a lower relative humidity, then the raindrops will evaporate again, before reaching the ground.

Clouds tend to form over ground that is covered with vegetation, where the soil can remain cool and damp, in the shade of the canopy. The rock and sand in dry desert country reflects more solar energy, that heats any clouds that may form. Those clouds then dissolve to become clear sky, allowing more solar energy to perpetuate more dry desert. Cloud seeding will NOT change desert into rainforest.

There have been studies investigating ways of using cloud seeding to increase the recharge of hydroelectric water storage in Tasmania. Those studies have shown cloud seeding to be unproductive, except in very special situations, circumstances that almost never occur.

 

[sophiecentaur]

The warm, dry, Santa Ana winds from the desert are the problem.

The situation with California's water supply has been brewing for decades. It's not widely reported here in UK so I can't claim to be totally across things but this link has a lot of worrying numbers.
John Steinbeck wrote about the results of unregulated agriculture, many years ago. Problems are not restricted to US; the Arral Sea turned into a desert because water was diverted from its sources for agriculture.
Climate deniers just add to the queue of dangerous influencers on our possible futures.

 

[DaveE]

The situation with California's water supply has been brewing for decades.

Yes, water has always been an issue in the West. Mostly for economic reasons. California is a huge agricultural producer.

But, these fires have NOTHING to do with the water storage and supply system.

 

[sophiecentaur]

But, these fires have NOTHING to do with the water storage and supply system.

That sounds strange but i guess I just have to accept that.