00:00They are a source of inspiration for dreamers, poets, and time-lapse enthusiasts.
00:06Clouds are also of great interest to science.
00:09They are, among other things, the single greatest source of uncertainty in current climate models.
00:15One way to study clouds is to climb 1,400 meters to the top of a dormant volcano,
00:21the Puy-de-Dôme, in central France.
00:23This is where Pierre Amateau and his team take samples of the atmosphere and of clouds when they are out.
00:30And so, we're going to get these places with this kind of material.
00:33It's just an aspirator, in fact, which will allow us to recover the little clouds that the clouds are made,
00:41and to recover them in condensed form, and to analyze them in the laboratory to study their content.
00:50But what exactly is there in a cloud?
00:53Water, of course, but also dust, traces of various chemicals, and even living beings.
00:59In these clouds, we have around 10,000 bacteria per milliliter.
01:04So it's not a lot, it's about what we have in the eau of the robinet.
01:08But 10,000 bacteria, it's not a thing.
01:09So where do they come, these bacteria?
01:12If you look around us, you can see that the surface of the Earth is covered by vegetation.
01:17All this is colonized by microorganisms, which, with the wind, will pass into the atmosphere,
01:22and, eventually, reach out to a very important altitude to be incorporated in the clouds.
01:28So the microorganisms that we have in the clouds are, most of the time, affiliated with the vegetal cover.
01:33And just like plants that absorb CO2 are large animals that produce greenhouse gases,
01:38these microorganisms have a role to play in the global carbon cycle.
01:42So, we're interested in their passage in the clouds, because they are in a aquatic environment,
01:48in which they will be able to transform some carbon carbon dioxide,
01:51the formaldéhyde, for example, which is a polluant, a toxic component.
01:56These bacteria will be able to assimilate and, in respirating, by example, to produce CO2.
02:01So they will produce CO2, which, on the sait, is a very important gas gas,
02:06and they will be able to, eventually, we don't know, we haven't really quantified it yet,
02:10but they will be able to, eventually, participate in the surface of the Earth,
02:12and, thus, influence the climate.
02:14Their exact role on the climate is still to be determined,
02:17but what is certain, on the other hand, is that these organisms can be responsible for the rain.
02:23That way, they actively arrange their trip back to the ground, inside a raindrop.
02:27They do this by making the clouds' water freeze.
02:30It's not an easy task.
02:31It's exceptionally pure water, can remain liquid, even at 10 degrees below zero.
02:37The rain samples that we collected from the summit of the Puy-de-Dôme is here,
02:41and what we are interested in is to isolate micro-organisms
02:45to study their properties in a lab.
02:48So, for that, we push them into a healthy environment,
02:52these micro-organisms living,
02:54and, then, we can isolate them, for example, here, in a liquid environment.
02:58So, here, we have a Pseudomonas,
03:00which is a group relatively frequent in the clouds.
03:02We find it about 50% of the time, in our samples.
03:05This bacteria can be able to get the water at a relatively high temperature.
03:13In this bain-marie, so, at minus 8 degrees,
03:15we have pure water,
03:17like the saw and saw the clouds,
03:18that's to say with very few particles.
03:20As we can see, the water is still liquid.
03:24and this bacteria, so, produces a protein that makes it geles the water.
03:28And, here, it makes it geles the clouds.
03:41So, why it's interesting for us, in fact,
03:44a sea that gèles under our latitude,
03:46and medium latitude,
03:47will tend to precipitate.
03:49So, this bacteria, finally, induces its own precipitation,
03:53and in the same time, the pluie, or the neige,
03:55and it will allow them to re-colonize the surface on the ground.
04:00In the context of climate change,
04:02it is essential to fully understand
04:04how all living beings fit into the complex climate models.
04:08Although, it must be said
04:09that some animals have a bigger impact than others.
04:29that have remains the place of nature.
04:30So, again, we'll have an initiate например in the cold
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