From NASA Science News: I’ve always wondered what cumulative effect increased global shipping might have on low level clouds over the ocean. These NASA images suggest ship cloud tracks are much like contrails following jets, though with differing mechanisms.
Clouds form when water vapor condenses or freezes onto tiny solid or liquid particles, such as dust, soot, or crystals of sea salt. Over the remote ocean, the air is usually cleaner than it is over land, so there are fewer particles to act as seeds for cloud droplets. The scarcity of particles means that the droplets that do form grow relatively large.
This pair of images demonstrates how air pollution can change the size of droplets in marine clouds. The top image is a photo-like view of the North Pacific Ocean (south of the Aleutian Islands) on September 29, 2009. A blanket of clouds—a little thin in places—spans the scene. The lower image shows the size of cloud droplets within the area outlined in white in the top image. Bigger droplets are darker colors (blue, purple); smaller droplets are brighter (pink, yellow).
The bright yellow arcs that streak the marine cloud layer are ship tracks—clouds that form when water vapor condenses onto the myriad tiny pollution particles in ship exhaust. There are more seed particles in ship exhaust than are found in clean marine air, and the available water vapor gets spread out more thinly among them. Because the available water is spread among more particles, the cloud droplets that form in the ships’ wakes are smaller than typical marine layer cloud droplets.
By increasing the number and decreasing the size of cloud droplets, pollution often makes clouds brighter (more reflective to incoming sunlight), in the same way that a crushed ice cube is more reflective than a solid one. In this image, however, the ship tracks don’t appear significantly brighter than the surrounding cloud layer, perhaps because the cloud layer was already fairly bright. (A March 2009 image from this area demonstrates the cloud-brightening effect more dramatically).
In marine layer clouds, an abundance of small particles may also delay the onset of precipitation, which depends on cloud droplets colliding and coalescing into larger, heavier drops. Said another way, pollution can increase the lifetime of clouds.
Human pollution has likely been modifying clouds on a global scale throughout the modern (industrial) era. In fact, climate scientists suspect that these modifications—increasing cloud brightness and lifetime—have probably helped offset some of the warming influence of rising greenhouse gas concentrations.
NASA Earth Observatory image created by Jesse Allen, using data obtained from the Goddard Level 1 and Atmospheric Archive and Distribution System (LAADS). Caption by Rebecca Lindsey.
- Instrument:
- Terra – MODIS
899 says:
July 24, 2010 at 5:22 pm
quote Your reply is rather specious given that the mentioned ‘clouds’ DON’T dissipate even when the surrounding natural clouds DO dissipate as the day wears on.
unquote
You obviously have access to a time series I have not seen — or real-time observations. Not having seen the observations you quote I can only suggest that if an air mass is deficient in CCNs then, once the introduction of smoke particles makes the droplets form, the artificially-induced clouds are more resistant to repeated evaporation. Try to think of it as being an observation of different clouds, one, the natural ones, with droplets not tightly bound to the salt particles, organic debris, dust, while the artifial droplets are more tightly bound to the strongly deliquescent artificial CCNs.
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Pretending as you do to declare that emissions of the vessels are white is as about as asinine a remark as any I’ve read lately. Show me a ship emitting white smoke and I’ll show you a ship that about to catch fire, because the flame in the boiler is running far too hot for the internals to sustain that condition for more than a few minutes as a time.
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I’m afraid you are leaping to conclusions not verified by the data. No-one, not even I, is saying that the ‘smoke’ emitted from the ships is white. It is usually transparent when viewed close to, although my observations of ships seen from a good missile engagement distance of several miles is that one can actually make out a black exhaust trail. Unless, of course, it’s the USS California.
quote I should know: My first four years in the USN were as a boiler tender on an aircraft carrier. Burning white is to be avoided in the same way a burning black, only black smoke tends to load up the piping with carbon and thence reduces the efficiency by dint of the fact that the carbon acts as an insulator on the pipes, which then requires more fuel to generate the same amount of steam.
unquote
Interesting but not relevant. No-one is claiming that the white trails are smoke: they are caused by the precipitation of water onto the CCNs in the exhaust.
quote And you’ve not explained how it is that a SMOKE trail causes water vapor to both collect as well expands into a opaque mass which covers literally HUNDREDS of miles in width. There isn’t that much smoke coming out of the stack!!
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The smoke doesn’t cause water vapour to collect. The _particles_ in the smoke collect water. Think about the smoke as being lots of particles very close together, so tiny as to be invisible. Now add water vapour and the particles become tiny but visible droplets, still densely packed. Then imagine the droplets spreading widely, still white, still visible. The spread-out clouds are not as white as the original as they’ve been ‘diluted’ by clean air, unless there was not enough water vapour to occupy all the CCNs –in that case more droplets will form when more vapour is available and the temperature is right for condensation.
A nice homely simile for what happens is a jug with a bit of milk in. White milk is droplets of fat suspended in water. Add more water and, for a surprisingly long time, the jug contents remain white, especially if you shine a very strong light on it as the droplets disperse through the bulk of the liquid. Eventually, as the dilution overwhelms the reflectivity of the droplets, the contents become bluish, transparent. Next time you get the chance to look up, study contrails and watch the same thing happening above your head.
I think in your assertion that these trails grow to hundreds of miles wide you are guilty of exaggeration.
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So, your explanation is so full of holes that it sinks into the waters of the ludicrous!
And once again you sidestepped the obvious question: How is it that said ‘ship trails’ shown in the pictures have coequal curvatures which bend in one direction, whilst an adjacent other set of trails are bending in opposition?
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You seem to labour under the misapprehension that the pattern of the trails matters in an explanation of how they form. Sorry, I cannot enlighten you about what the ships are doing and why the trails are curved.
quote Additionally, those trails appear BOTH adjacent to land as well as in the wide-open expanses of the ocean. Some appear right adjacent to large cities. So your hypothesis fails on that aspect alone: WHY are not the cities producing that same amount of clouding from their surface traffic?
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I find this statement confusing. Air mass conditions are relevant, location on the globe not so much. If you find ship trails near areas which you find unexpected then I suggest you study where the airmass has come from, not its current location.
A city is generally built in an area where the air is less likely to be saturated and will generally not be deficient in CCNs. Both these conditions are required to make a contrail/exhaust trail. If you produced large quantities of CCNs and let them drift in their uncounted trillions over the oceans then all the areas which are at the right temperature and humidity to form clouds will do so. Only when the conditions are right and there are too few CCNs do these trails form. The air is supersaturated with water vapour, waiting for a particle like a cloud chamber waits for a sub-atomic particle.
You use your own observations about exhaust trails to buttress your arguments — please consider the difference of viewpoint from the ship and from the air. From the ship you see only a few miles — the CCNs from the exhaust are not yet spread out by turbulence and may not have reached a region where the temperature and the humidity are right for droplet formation. From the air one sees for tens of miles and the trails will, in the correct conditions, have had time to form as local turbulence lifts and disperses them into the right conditions for the water vapour to condense on them.
HTH.
JF
(Who had to look up ‘specious’. Better ‘superficially attractive’ than not attractive at all….)
Julian Flood says:
July 25, 2010 at 1:18 am
You obviously have access to a time series I have not seen — or real-time observations. Not having seen the observations you quote I can only suggest that if an air mass is deficient in CCNs then, once the introduction of smoke particles makes the droplets form, the artificially-induced clouds are more resistant to repeated evaporation. Try to think of it as being an observation of different clouds, one, the natural ones, with droplets not tightly bound to the salt particles, organic debris, dust, while the artifial droplets are more tightly bound to the strongly deliquescent artificial CCNs.
DO TELL: WHY has the ‘effect’ not been observed until most recently?
WHY was the effect NOT observed in the U.S. Civil War, or the Spanish-American War, or WWI, or WWII, or the Korean War, or the Vietnam War? In all of those, internal combustion engines —of various sorts— were employed, yet no such ‘clouds’ were ever to be observed.
You pretend to say that “smoke particles makes the droplets form, the artificially-induced clouds are more resistant to repeated evaporation.”
DO TELL: What conditions are necessary for such to manifest themselves?
And: In what laboratory has such a condition been shown to exist?
The rest of your remarks are irrelevant until you affirmatively address the above.
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The rest of your remarks are irrelevant until you affirmatively address the above.
unquote
I’m sorry, you are either unwilling to use your brain or a troll*. Try and do a bit of research, then come back when you have a basis on which to argue.
It’s possible, of course, that I have the wrong end of the stick and ship tracks are an entirely new phenomenon which has been produced by a conspiracy of men in strange black helicopters.
BTW, what do you think they are?
JF
*or a very advanced LISA being tried out of the lab. If the last then I congratulate your programmers.
@ur momisugly Julian Flood says:
July 25, 2010 at 1:51 pm
*
*
[1] You made no attempt to reply to my germane questions above regarding the lack of history of the supposed ‘ship tracks.’ They were not observed priorly, and there are no dated historical references for such.
[2] As for a fact, in NONE of the photos is there a wake produced by the ‘supposed ships.’ Certainly if one may see the effluent emitted from the stacks with such clarity, then the ships wakes —being far more visible from space than their stack exhaust— would have evinced themselves even more readily.
[3] I take due and careful note that you completely avoiding addressing why it was that there are parabola being generated in opposing directions. If you wish to declare that the wind caused one set, then it could NOT have caused the obverse bending in the upper set.
[4] Apparently you are given to believe virtually everything you read when it’s sourced by an agency of government.
[5] You have nothing of substance which supports any theory you might put forward.
[6] I have both the experience and information which reveals that said ‘ship tracks’ are artificial in nature and are not moisture by any stretch of the imagination.
[7] Further, I take note that since you can’t provide historical proof of the matter, whereas I can, that you engage in the ad hominem by tossing out the ‘conspiracy’ word. That, after all, is the modus operandi of someone who’s been called out and has nothing of substance to support his contentions. Yes, if you can’t support your theory, why just call the other guy a ‘conspiracy theorist’ in order to deflect attention away from yourself and your piss-poor theory, all the while hoping that no one’s paying attention whilst you cast aspersions.
[8] Since the historical record reveals no such tracks being generated by ship stack gasses, and the available photos reveal NO wakes by the supposed ships, then the only logical conclusion is that the tracks were made by aircraft. The government agency says ‘ship tracks’ and I say BS! You know what I think? Somebody in Alaska called asked about all that crap in the sky and who’s responsible for it. So along comes an agency of government, and it cooks up a neat lie, hoping to explain away the whole thing by resorting to the latest scam: CAGW/CCC. The first ‘C’ in both cases stands for ‘Contrived.’
[9] Finally, contrails produced by aircraft turbine engines are the result of dense moist air being compressed, heated and mixed with fuel, combusted and expelled. The result is steam released with the combustion products.
Since the combustion products are essentially too thin to actually be seen, the only visible effect is the steam, itself which dissipates gradually, and in doing so quite rapidly changes from opaque to translucent to transparent and finally dissipates entirely. The whole process takes less than an hour at altitude, and sometimes a bit longer at lower altitudes, but NEVER does it expand to cover HUNDREDS of miles in width and remain completely opaque, hanging around for SEVERAL hours, and sometimes days.
THAT IS NOT MOISTURE by ANY stretch of the imagination, and it is MOST CERTAINLY NOT exhaust gasses either. The quantity of engine fuel needed to produce any such effect would be absolutely horrendous, and the engine would need to be far, far larger than anything available or in use at the present.
So then, I’ve already identified what those trails are not. What remains is to determine their composition by actual collection of them.
quote
[9] Finally, contrails produced by aircraft turbine engines are the result of dense moist air being compressed, heated and mixed with fuel, combusted and expelled. The result is steam released with the combustion products.
Unquote
Thanks for that explanation, I’ve always wondered what they were made of. And the ones that spread — I have actually seen it happen — are obviously something different. It’s all clear now.
And the ship tracks are a cover story for trails which NASA is lying about because it’s physically impossible for a contrail to last for that long. OK. So someone is making trails in the sky for unknown purposes and government or an agency is covering up the real reason.
Now I understand.
I say nothing abut why they trace out parabolas because I don’t know. Surely you agree with Wittgenstein’s dictum about what to say about things one does not know about, i.e. ‘Whereof one cannot speak, thereof one must be silent’?
JF
(I agree with you about collection of the stuff. There should be a lot more actual research into these matters.)