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The coldest clouds

By: Dr. Jeff Masters, 5:21 PM GMT on December 15, 2005

In the wunderphoto posted by carlskou today (see image below), the caption reads: What's that? Well, I'll answer that question!

That is a Polar Stratospheric Cloud (PSC), also known as a nacreous or mother-of-pearl cloud. These clouds of ice crystals form in the very coldest reaches of the stratosphere over both poles in winter, at an altitude of 25-30 km. These ice-crystal clouds are frequently iridescent, meaning that they diffract the suns's light and form brilliant spots or borders of colors, usually red and green, up to about 30� from the sun.

Polar Stratospheric clouds are fairly rare, because they require extremely cold temperatures that are not often found in the atmosphere. However, residents of Norway, Sweden, Finland, Alaska, northern Canada, and other polar locations can expect to see a lot more of these in the future. Why? Because the stratospere is cooling. The Arctic stratosphere has cooled 3�C in the past 20 years due the combined effects of ozone loss, greenhouse gas accumulation, and natural variability. Winter 2005 temperatures in the Arctic stratosphere were the coldest ever recorded. A large part of this cooling is due to the greenhouse effect. Yes, the surface and lower atmosphere are warmed by the greenhouse effect, but this means that the atmosphere must cool somewhere else to compensate. Much of this cooling happens in the stratosphere. This can best be understood by considering that the Earth is in "radiative equilibrium"--the amount of solar energy coming in is balanced by the amount of energy going out. Surface warming must be balanced by upper-atmosphere cooling, since the amount of solar radiation the Earth receives does not change, and satellite measurements have shown that the amount of heat going out to space from the Earth has not changed, either.

What does all this stratosperic cooling mean for the climate? That is mostly unknown. We do know that PSCs act to greatly accelerate stratosperic ozone destruction, since the chemical reactions that destroy ozone happen much faster on the reactive surfaces that PSCs provide. A recent model study (Rex et. al., 2004), indicates that future Arctic ozone depletion could be much worse than expected, and that each degree Centigrade cooling of the Arctic may result in a 4% decrease in ozone. This ozone loss will occur despite the fact that concentrations of ozone-destroying chlorofluorocarbons (CFCs) are no longer rising, thanks to the international agreements that have phased out CFC use. It's a very good thing that the nations of the world acted quickly and effectively to ban CFC use when they did, or else we would have likely seen an Arctic ozone hole open up each Spring to complement the Antarctic ozone hole.

Tomorrow's topic: Penetrating tornadoes with modified vehicles.

Jeff Masters
What's that?
What's that?
Seen near Kuummiut East-Greenland.
Storm Behind the Mountains 2
Storm Behind the Mountains 2
Beautiful sunset with Polar Stratosferic Clouds and all colours of the rainbow. This fenomena happens about 20-25 km up in the atmosfere in the middle of the winter when the air moves fast, in the sunset and a little after. You can see the sun in the pictures lower left.
Nacreous Clouds
Nacreous Clouds
Nacreous Clouds over Hut Point Nacreous means "pearlescent"or mother of pearl like.. but these clouds are really not true clouds, even though they are classified as such. They do not form as a true cloud does. During the spring and fall in Antarctica, the chemicals that are depleting the ozone, get cold enough to "stick" to each other and form these clouds. In other words, they are formed by chemical bonds..

Atmospheric Phenomena

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

OoooooooH! cool images!
How come I never see anything neat like that in the sky? Must be my karma....


Posted by: JeffMasters, 11:42 AM EST on December 15, 2005

The Arctic stratosphere has cooled 3C in the past 20 years ... Surface warming must be balanced by upper-atmosphere cooling, since the amount of solar radiation the Earth receives does not change, and satellite measurements have shown that the amount of heat going out to space from the Earth has not changed, either.


Jeff,

I thought the concept of greenhouse gasses was that it reduced the amount of heat being radiated into space.

Your post indicated that said radiation has NOT decreased.

What is the mechanism by which greenhouse gasses allow the same radiation to pass, but somehow absorb heat from the stratosphere above?

Also, has anyone calculated what the total energy of a 3 degree reduction in stratospheric temperature would be, and is that figure about equal to the calculated energy of the corresponding increase in temperature of the troposphere, land masses, ice masses and oceans?
Who needs a modfied vehicle to penetrate tornadoes? Let's use graduate students!
lol snowski
In order for rapid ozone destruction to happen, clouds (known as PSCs, Stratospheric Clouds Mother of Pearl or Nacreous Clouds) have to form in the ozone layer. In these clouds surface chemistry takes place. This converts chlorine or bromine (from CFCs and other ozone depleting chemicals) into an active form, so that when there is sunlight, ozone is rapidly destroyed. Without the clouds, there is little or no ozone destruction. found that at theozonehole. Sometimes it's the prettiest things that hurt & kill us. hhuuummmm~ how do we suck up or disapate these clouds. This was also quite interesting~ an artic ozone hole is being forcasted to form due to an in increase in volcanos, so named the volcanic ozone hole

TampaSteve ~ thanks for the answer on the storm that kept crossing the equator. I thought i'd remembered seeing it on tv infront of people i worked with, perhaps at the work bar, being busted as a weather geek. Had kinda put it out of my mind, including what a wild (hopefully, once in a lifetime) storm that was. & yeah that was days ago, my problems weren't my modem~ DSL & still tempermental.
Dr. Masters,

Do we know what physical mechanism causes the stratosphere to cool as the ground (and I guess troposhere) heat up? I understand that it's happening, observationally verified. I'm curious if we have any idea how it happens.\

Thanks,

Mike Cotton
Dr. Jeff, thanks for your continued Wunderblog posting. I look forward to your new posts as they are always educational.
Dr Masters,
Once again a very interesting udate. Looking at these blogs really gives us a lot of good information. A lot of learning is going on here but much more fun than when in school! Thanks again for the information and looking forward to your other future topics!
Gamma
I almost never see anything cool in the sky here in Southern California. To much Smog and a lack of real storm systems. The coolest thing I ever saw was a funnle cloud. A very cold storm from the Gulf of Alaska late in the winter season (March) came down and pulled up some warmer moister air from Mexico(None of the computer modles at the time where expecting it to come in as strong and with extra mositure). There was a funnle cloud over my city for a few minutes. I was at PE class at the time and I watched it as it moved accoss the sky. It disapated almost faster then it came. It weakend and brought some hail and a very heavy downpore. Then after that the sun came out and the local news hellocopter was fallowing that thunderstrom. Thats my story of the day.
Stratospheric clouds? Cool...those pictures are amazing.
It's spelled "funnel", by the way.
In order for rapid ozone destruction to happen, clouds (known as PSCs, Stratospheric Clouds Mother of Pearl or Nacreous Clouds) have to form in the ozone layer. In these clouds surface chemistry takes place. This converts chlorine or bromine (from CFCs and other ozone depleting chemicals) into an active form, so that when there is sunlight, ozone is rapidly destroyed. Without the clouds, there is little or no ozone destruction. found that at theozonehole. Sometimes it's the prettiest things that hurt & kill us. hhuuummmm~ how do we suck up or disapate these clouds. This was also quite interesting~ an artic ozone hole is being forcasted to form due to an in increase in volcanos, so named the volcanic ozone hole

TampaSteve ~ thanks for the answer on the storm that kept crossing the equator. I thought i'd remembered seeing it on tv infront of people i worked with, perhaps at the work bar, being busted as a weather geek. Had kinda put it out of my mind, including what a wild (hopefully, once in a lifetime) storm that was. & yeah that was days ago, my problems weren't my modem~ DSL & still very tempermental.
Good evening. Are these the same as Noctilucent clouds, or are these different?
Anthony
what up this big high over ca keep going and going and going and going and going will it ever move out of ca yes it will by time this week end is her ca will get some light rain and light snow and snow level arould 5500ft to 6,000ft and more rain for next week to so wet weather is comeing to ca for this weekend and end to next week

in jeff photo there what kind of clouds or there?
16. Inyo
Lightning: if you want to see neat weather in southern California just go out to the Mojave Desert or Owens Valley during monsoon season. Although the storms generally arent quite as intense as the midwestern variety, they are in my opinion more impressive/beautiful in many cases, due to the extremely high air visibility, the amazing setting, the abundance of dry nightning, etc.

I've seen funnel clouds in the Central Valley but never in so-cal. the closest i've ever seen was out of some weird little high-based 'storm' building off of a gust front (maybe it was a 'gustnado' or something?) There was a strongly rotated cloud base, i watched it for about 30 seconds then went inside to get my camera, when i got back it was gone, although some weird horizontal cirrus-type vertexes were in the sky after that.

I was also in a storm this year with deafeningly constant thunder and intense marble sized hail, up in the vicinity of Mt Wilson. Mountain weather is infinitely more interesting than the weather down in the city.

Katrinarita, from my experience, we don't usually get pounded by big storms until around/after Christmas down in southern California. So i'm not worried about a dry year quite yet. The high should break down any minute now, really (actually most recent indications are for a nor-cal storm on Sunday and one for the entire state on Thursday.. but that's 7 days away, so it may never happen)
8889,
what's the weather been like in ca, and how about those 49ers?
I can't wait for Dr. Masters' entry tomorrow! I read a book called Big Weather by Mark Svenvold that talks about a guy trying to intercept a weak tornado.
phelp the weather in ca will get wet this weekend and in to next week and i do like the 49er
Actualy it is not the cfcs falt as most sientists think no time to explain right now but the reson is simpler than you would think..................


Posted By: mfr751 at 12:24 AM GMT on December 16, 2005.

Good evening. Are these the same as Noctilucent clouds, or are these different?


Noctilucent clouds (also called Polar Mesospheric Clouds) are different from nacreous clouds:

Noctilucent clouds occur in the upper mesosphere, at about 80 km. Their name derives from the fact that they can be seen from the ground when the Sun is 7-10 degrees below the horizon and only reflects off these very high clouds. It arises from the water vapour released upon oxidation of methane. Noctilucent clouds are most common in the summer in polar regions. At this time the mesospheric lapse rate is
close to neutral, and this makes uplift easier.

Noctilucent Cloud Information:

http://freespace.virgin.net/eclipsing.binary/whatarenlc.html
map_tropinfo24_ltst_5nhato_enus_600x405
That is one of the most beautiful things I've ever seen!
I think because last season it was so rainy in southern California that we where all expecting another insane season of rain. All indications as of right know are not looking so hot. I think we will be lucky to get an average rainy season. What I am worried what will happen is because of the rain we had last season was so extreame that this season it will be the extreame opposite. A very dry season.

Inyo
I have always wanted to see the Thunderstorms in the desert. Sadly I rarely leave the county. Once in a while at summer time I can see thoes Thunderstorm clouds over the gabriel's and if its clear and I go out at the right time around sunset and if there is enough lightning with the storms you can see them light up. I remember this one night at the season opener of the football game last year (I am in 12th grade this year) there was a great viewing where I was watching the stomrs more then the game.

lightning10 i love lighting storms at night they are so cool and some time we get a few up her too but why do ca do not get t storm like they do in tx the lighting show in tx go on more then it dos in ca why is that?
29. Inyo
yeah lightning, it is awesome to watch the mountain storms in the summer but kind of frustrating beacuse they so rarely come down into the city. Now that i work in the high mountains, though, i will be up in them! Once you get out of high school you will get more of a chance to roam around and check out neat stuff.

also, as for the wet/dry thing... most wet years are actually followed by dry years.. i read a scientific paper a while back about how, while dry years in southern california train together, wet years generally don't. The year after the wettest year on record, was the second driest year on record. So, by that pattern, it will be dry. The reason i speculate it may still be above average is just that the storms everywhere are acting unusual, everything is out of whack, we could get some weird, unexpected storms. However, it just as easily could be dry. Hope for rain, prepare for drought, i guess.
30. Inyo
oh sorry for the double post but coastal CA doesn't get many summer thunderstorms because
-the cold coastal inversion tends to kill them
-summer monsoons come from the east, and hit the mountains and make rain up there. Coastal California is in the rain shadow from storms coming from the east, in the same way the desert is in the rain shadow during pacific storms. It is rare for storms coming from the east to survive the trip over the mountains.. the only case you see it is during some kind of strange low pressure system.. or if the storms actually come off of the ocean from a dissipating tropical system.
Check this out!!



^^ One of the Mesosphere clouds ^^
Colby, what a beautiful picture! Thanks for sharing.
Yes I found a way to post at school. This school has the most web sites blocked probally out of any school in the district. Dont worrie its a free internet period today on account its the last day before the holliday.

Anyways I was thinking over the past few years where I live I have sceen a lot more thunderstorms in the summer time. I i would love to see more but i know that it is very unlikely.

I was thinking would we get more rain durning the summer time if we where to someone cut Baja Mexico off and if there was ocean to the south and the water stayed warm we would get more rain from the south. It acks as a big shield from moisture trying to get into most of the areas of Southern California.
Nice day here in Central Fl...partly cloudy and 61
35. Inyo
the monsoons in the Southwest do seem to have stepped up in the last 5 years, or maybe since 1998. Since they are heat-driven, it would make sense for this to happen if the climate warms.

I think the only reason the Sea of Cortez is so warm is beacuse of Baja.. if you cut it off the California Current would probably just push the hot water away... i think
Hey 21? You still here?
Does anyone here know how to view the sent items in your mailbox? I'm trying to look for mine and can only view "inbox"

Thanks for any feedback.
You know folks, a person who was unaware about electricity might just reach out to grab a lightning bolt. That's exactly how you are reacting to photos of chemical pastels swatching across the sky. In fact, those images look like something one might encounter looking from inside a spacesuit on a dead planet.
these clouds are nothing more than CHEMTRAILS. The lines that are lain by airplanes are still very visible in the picture posted by ForecasterColby.

Weatherwars.info

this guy may be a kook but he's on to something. Time to wake up, everyone! Our freedom comes at a very high price.
I've only seen a nacreous cloud once - it looked like an ordinary cloud at first and then turned all colours of the rainbow. The phenomenon lasted around five minutes as the cloud passed the sun. Oddly enough, it was just north of Nairobi, Kenya on the equator.
cookie...that could have been an ordinary cirrus cloud...you can get rainbow effects or "sundogs" in the cloud because it's made of ice crystals
I thought a sundog was a fake sun formed by ice crystals in the air. I've seen one or two before. I've never seen the colored cirrus cloud phenomenon before or since, but it was one of the coolest things I've seen.