Earth's Clouds Are Getting Lower, page 1


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Topic started on 24-9-2012 @ 07:47 AM by smyleegrl
Greetings, ATS!

Last week I was listening to NPR and they had an interesting story about the clouds covering our planet. According to the reporter, the average height of clouds has been getting lower over the past few years.

That was the extent of the story, so I did a little digging. Here's what I've found:

Science Daily

The study, published recently in the journal Geophysical Research Letters, revealed an overall trend of decreasing cloud height. Global average cloud height declined by around one percent over the decade, or by around 100 to 130 feet (30 to 40 meters). Most of the reduction was due to fewer clouds occurring at very high altitudes.


Scientists have only recently (past decade) begun to study this phenomenon, so its premature to make long-term predictions.

If the clouds are indeed lowering, what effect can we expect?



A consistent reduction in cloud height would allow Earth to cool to space more efficiently, reducing the surface temperature of the planet and potentially slowing the effects of global warming. This may represent a "negative feedback" mechanism -- a change caused by global warming that works to counteract it. "We don't know exactly what causes the cloud heights to lower," says Davies. "But it must be due to a change in the circulation patterns that give rise to cloud formation at high altitude."


So if we combine this information with the information about the solar hibernation, does it indicate a higher possiblilty for a cooling trend in the future?


reply posted on 24-9-2012 @ 08:48 AM by smyleegrl
reply to post by Vasa Croe



Apparently it will do the opposite, and make things cooler. Kinda is an oxymoron, which is what startled me. I always thought that clouds held the warmth in, so it's confusing.


reply posted on 24-9-2012 @ 09:19 AM by Fazza!
reply to post by smyleegrl



Clouds help to insulate the Earth - thicker clouds will keep more heat in the boundary layer. The article is suggesting a decrease in mean global cloud height (thickness) has been observed which effectively reduces the thickness of Earth's insulation. A cooling effect is the result of this.

...satellite data show that cloud optical thickness actually increases with increasing temperature. Whether the net effect is warming or cooling depends on details such as the type and altitude of the cloud; details that are difficult to represent in climate models.

Source

These feedback mechanisms seem to oscillate. 'Global warming' = warmer seas and more evaporation which leads to thicker clouds. More heat is trapped so there is more evaporation and clouds get thicker. Eventually they reach a critical point where the cloud albedo is so high that more sunlight is reflected than reaches the Earth's surface and we start to see a cooling effect. This leads to a decrease in the rate of water evaporation and we observe lowering cloud heights. As more sunlight starts to reach the surface the process starts over (more evaporation and increasing cloud thickness).

The amount of ice at the poles and high latitudes also plays an important role in global warming / cooling with similar feedback mechanisms regarding surface albedo and ice melt.
edit on 24/9/2012 by Fazza! because: (no reason given)



reply posted on 24-9-2012 @ 09:44 AM by DIRTYDONKEY
The study of clouds, where they occur, and their characteristics, play a key role in the understanding of climate change. Low, thick clouds primarily reflect solar radiation and cool the surface of the Earth. High, thin clouds primarily transmit incoming solar radiation; at the same time, they trap some of the outgoing infrared radiation emitted by the Earth and radiate it back downward, thereby warming the surface of the Earth. Whether a given cloud will heat or cool the surface depends on several factors, including the cloud's altitude, its size, and the make-up of the particles that form the cloud. The balance between the cooling and warming actions of clouds is very close although, overall, averaging the effects of all the clouds around the globe, cooling predominates.
LINK

pretty good description at link, as well as diagrams. Lowers clouds do lower temp. Thanks for sharing S&F from me

The shortwave rays from the Sun are scattered in a cloud. Many of the rays return to space. The resulting "cloud albedo forcing," taken by itself, tends to cause a cooling of the Earth.

Longwave rays emitted by the Earth are absorbed and reemitted by a cloud, with some rays going to the surface. Thicker arrows indicate more energy. The resulting "cloud greenhouse forcing," taken by itself, tends to cause a warming of the Earth.


It would appear the planet is taking care of itself, no surprise there.
edit on 24-9-2012 by DIRTYDONKEY because: (no reason given)
edit on 24-9-2012 by DIRTYDONKEY because: get it right



reply posted on 24-9-2012 @ 10:12 AM by new_here
I hope this is not due to atmosphere shrinkage. There was a lot of info about this in 2010... but can't find anything current.

Some articles about Atmosphere Shrinkage

And if it's true, could solar winds be the cause?
Solar wind controls nonthermal escape of planetary atmospheric volatiles, regardless of the strength of planetary magnetic fields.

Link


reply posted on 24-9-2012 @ 03:05 PM by MadQuacker
reply to post by badnickname



But wouldn't the water molecules still be in the atmosphere? so they would still be able to reform into natural clouds. Or where do you suppose they go? Just hanging on to the exhaust and gone forever?


reply posted on 24-9-2012 @ 04:43 PM by Afterthought
Here's a thread about an article from this past February talking about NASA's statement regarding the lower cloud tops. www.abovetopsecret.com...
It seems this situation is being brought into the spotlight again and reinforced for some reason.



reply posted on 24-9-2012 @ 06:57 PM by Phage
If the clouds are indeed lowering, what effect can we expect?

The thing is, the study didn't exactly find that clouds are "lowering".
Most of the reduction was due to fewer clouds occurring at very high altitudes.
www.sciencedaily.com...
Fewer high altitude clouds means a lower average cloud top height. That is what the study found.


The conclusion from the actual article:
Ten years is unfortunately too short a span for any definitive conclusion, as the linear trend in global cloud height of -44 +/- 22 m over the last decade is partly influenced by the La Niña event, and may prove ephemeral.

www.worldclimatereport.com...
Interesting chart there showing that the apparent trend was quite strongly influenced by La Nina. There is not enough data to indicate any trend at all but it does add another factor to demonstrate how complex the Earth's climate system is.


reply posted on 24-9-2012 @ 06:59 PM by Phage
reply to post by Afterthought




It seems this situation is being brought into the spotlight again and reinforced for some reason.

The article in the OP is from February.


reply posted on 24-9-2012 @ 07:06 PM by Phage
reply to post by benrl


Isn't funny, contrails cool the planet, on 911 when they stopped air traffic the temp actually rose.

Who says contrails cools the planet?

No. The temperature did not actually rise when air traffic was stopped after the attacks. What one study found was that the diurnal temperature change became greater. The study found that contrails sort of stabilize the day/night change in temperature by an average of 1º, keeping it a bit warmer at night and a bit cooler during the day. No net warming or cooling effect was indicated by the study but it does reinforce other studies showing that contrails have a net warming effect.
edit on 9/24/2012 by Phage because: (no reason given)

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