There have been a lot of posts on ATS of late from folk claiming that scenes like this:
or even this:
are evidence of stratospheric geoengineering, rather than just common or garden commercial aircraft contrails.
However, it's quite clear that they occur well within the troposphere - not the stratosphere - the same region of the atmosphere in which nearly all
other clouds occur . Whatever they are, they are emphatically NOT in the stratosphere nor evidence of geoengineering.
(commercial aircraft do often fly in the very lowest reaches of the stratosphere - however contrails typically form when they are moving through the
troposphere - which is why we can often see the aircraft themselves with the naked eye)
But that does not mean that, as some allege, that proposed projects for stratospheric geoengineering - usually suggested as a means of preventing
global warming - are not occurring.
The idea for stratospheric geoengineering originated when it was discovered that large volcanic eruptions eject huge amounts of aerosols - notably
sulphates - into the stratosphere and that these have a the effect of cuasing global cooling. After the Pinatubo eruption in 1991 there was a
noticeable drop in global temperatures
. If we could replicate the
effects of such an eruption, then we might counter the effects of, what is in effect another form of geoengineering - anthropogenic global warming.
That's the theory.
It's worth noting that most volcanic eruptions do not eject material into the stratosphere - indeed, that was the problem a year ago when Eyja
erupted in Iceland: the eruption threw ash only around 20,000ft up into the atmosphere, well below the stratosphere, and this meant that aircraft
flying to/from Europe had to fly through the ash cloud when taking off/landing. As this presented a danger to aircraft, flights were cancelled. As
I'm sure we all recall. Had it been a more masisve eruption and the ash had been sent into the stratosphere - well above the level at which aircraft
normally fly - there would not have been a problem!
Now, given that any such stratospheric geoengineering operation would involve aircraft flying much higher than normal, and spraying into a region of
the atmosphere where clouds do not normally form, is there any way we could see it happening? Well maybe there is.
There are in fact clouds which do form in the stratosphere (note: some very big cumulonumbus clouds may also extend upwards into the stratosphere) and
these are commonly referred to as nocties. Nocties, or noctilucent clouds, are usually seen at high to mid latitudes in mid summer. June and July
are the best months in the northern hemisphere. They form in the stratosphere and only become visible because they reflect sunlight when the sun is
below the horizon. They are best seen an hour or two after sunset or before sunrise. And they look like this:
Interestingly, there has been a big increase in sightings of nocties in recent years. Some attribute this to low solar activity. It has also been
suggested that exhaust from the space shuttle
may be aiding their
It is also occasionally possible to see other evidence of stratospheric clouds - specifically those (as mentioned above) caused by massive volcanic
eruptions. Such clouds may more readily manifest themselves in the form of vibrant sunsets -
were taken after the Sarychev eruption in 2009. But
such ash clouds can also be visible - just - to the naked eye. Hopefully you can make them out in these photos I took around the same time:
Note: these pictures have been enhanced to adjust the contrast and make the clouds more obvious. This is the sort of view seen at sunset at the
but the stratospheric clouds are not that obvious! You can see them better in this enhanced version:
they can been seen in this picture as ghostly, blue-white wisps - not dissimilar in fact to nocties!
Like noctilucent clouds, these volcanic clouds are also not visible during the daytime - but they can been seen closer to sunset/sunrise than
So, that's stratospheric clouds for you. Not easy to see! But if spraying in the stratosphere is taking place, that's the sort of thing we should
be looking out for.
Note: one of my hobbies is photographing meteorlogical phenomena. I have also been issuing weather forecasts on the internet since 2004, have a
number of friends who are professional meteorologists, and have a job which provides me plenty of time for surfing the internet through the day, and
finding interesting stories, articles and scientific papers - some of which I then post up for reference on my blog (see link below). None of which
should, however, have any real relevance - but I thnk it's useful before you ask any questions to have some idea of my background.