The CLOUD experiment at CERN has shown that before the industrial revolution the atmosphere was much cloudier than scientists had previously thought (Image: Maximillien Brice/CERN)
Our planet’s pre-industrial climate may have been cloudier than presently thought, shows CERN’s CLOUD experiment in two papers published today in Nature.
CLOUD shows that organic vapours emitted by trees produce lots of aerosol particles in the atmosphere when there’s no sulphuric acid – a main product of burning fossil fuels.
Previously, it was thought that sulphuric acid was essential to initiate the formation of these aerosol particles but the new research shows that these so-called biogenic vapours are also key to their growth, and can help them grow up to sizes where they can seed clouds.
“These results are the most important so far by the CLOUD experiment at CERN,” said CLOUD spokesperson, Jasper Kirkby. “When the nucleation and growth of pure biogenic aerosol particles is included in climate models, it should sharpen our understanding of the impact of human activities on clouds and climate.”
The Intergovernmental Panel on Climate Change (IPCC) considers that the increase in aerosols and clouds since pre-industrial times represents one of the largest sources of uncertainty in climate change. The CLOUD experiment is designed to better understand such processes.
CLOUD has also found that ions from galactic cosmic rays strongly enhance the production rate of pure biogenic particles – by a factor 10-100 compared with particles without ions. This suggests that cosmic rays may have played a more important role in aerosol and cloud formation in pre-industrial times than in today’s polluted atmosphere.
A modest ‘webcam’ on Mars Express has proven useful for outreach, education and citizen-science. Now ESA have decided to adopt it as a professional science instrument.
This sharp telescopic field of view holds two bright galaxies. Barred spiral NGC 5101 (top right) and nearly edge-on system NGC 5078 are separated on the sky by about 0.5 degrees or about the apparent width of a full moon. Found within the boundaries of the serpentine constellation Hydra, both are estimated to be around 90 million light-years away and similar in size to our own large Milky Way galaxy. In fact, if they both lie at the same distance their projected separation would be only 800,000 light-years or so. That's easily less than half the distance between the Milky Way and the Andromeda Galaxy. NGC 5078 is interacting with a smaller companion galaxy, cataloged as IC 879, seen just left of the larger galaxy's bright core. Even more distant background galaxies are scattered around the colorful field. Some are even visible right through the face-on disk of NGC 5101. But the prominent spiky stars are in the foreground, well within our own Milky Way.
