Tag Archives: Atmosphere

I’ll take my science with a side of sun, sea and surf…

Sometimes you need to reset, to remember that you actually do enjoy your job, and take time out for inspiration.  This was one of those days…

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On a gorgeously sunny Friday, we got to go on an atmospheric chemistry themed lab tour of UC San Diego and the The Scripps Institution of Oceanography and it was pretty much the best (work) day ever!

Our day started in the Bertram lab, learning about experimental techniques for measuring reactions on sea salt aerosols.  Another cool experiment involved measuring how good different aerosols are at forming clouds – acting as cloud condensation nuclei.  They also described some of the challenges of getting ready for a field campaign such as the CARES campaign, or the GOAMAZON campaign.  These campaigns are organized years in advance and the deadlines are very strictly adhered to so once a commitment has been made by a group to participate, they absolutely must be ready on time.  This often involves building and testing new instruments, I know plenty about the pressures of working to deadlines but this stuff is on another level.

Then to the Thiemens lab, led by the super cool prof Thiemens – if you ever get a chance to attend one of his talks/lectures, you won’t be disappointed.  They work on very painstaking analysis of chemicals and rocks using radioactive isotope analysis.  As a result they are able to work out where things came from and how long they have been around.  They have made measurements  in the Arctic, the Antarctic, the Himalayas, even on meteorites from Mars and moon rocks.  We also heard  a little about Snowball Earth, something I had never heard of but I’m adding it to my reading list.

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An ATOFMS in the Prather lab UCSD

The Prather lab was full of the most kick ass machines – several aerosol mass spectrometers (ATOFMS) which the group actually developed and built themselves.  Take my word for it, this is pretty amazing.  They are using them to analyse aerosols in laboratory experiments and putting them on aeroplanes to monitor the real atmosphere.  They are even using one of them to look for markers in cancerous cells.  I loved that they all have names, like Shirley, Jake and Elwood!

What else? What else? Oh yes, the best part (don’t tell anyone but i’m thinking of changing career and becoming a deck hand), the Scripps Institute Hydraulics lab and Pier.  The lab contains a wind wave channel which is a 45 m long and 2.5 m wide channel filled with water.  At one end is a giant paddle that creates waves and at the other end is a massive fan that generates the equivalent of a mini hurricane to break the waves.  Luckily for us, the director of the institute was there and he cranked it up for us.  As you watch through the glass sides you see wave after perfect wave breaking right in front of you.  The wave channel is used to study in a controlled environment, what happens when waves breaks, from physics (how the energy of the wave is spent) to the chemistry (hooking up with UCSD chemistry scientists to measure what and how sea salt particles and gases such as carbon dioxide are exchanged with the air above the sea).  They also use it to test their very expensive equipment, before unleashing it, and quite possibly losing it, in a real storm in the middle of the ocean.

Last was the Scri2013-04-19 14.26.33pps pier, the perfect last stop.  Equipped with an array of weather monitoring systems and boats for sampling out at sea.  The icing on the cake, a leopard shark basking beneath us and a seal joining in with the surfers.  Good job UCSD, but talk about setting the bar high!

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Make it rain up in here

Coming from the UK, I have an unhealthy fascination with the weather.  The never ending, will it – won’t it rain tomorrow? Will we get a day off school if it floods? Might it snow? Will we get snowed in? Talking about this is practically a national pastime, if weather worrying were an Olympic sport, we’d get gold every time.

Snowy Glynhir

Despite this early ‘training’ I only recently learned a little about how rain and snow actually forms.  An important lesson is that water can’t condense onto itself  to form rain droplets or snow flakes.  There needs to be a seed particle present and these seeds are known as aerosols.  An aerosol being a particle of one phase (such as a solid or liquid) suspended in a different phase (such as a gas).  So our seed particles are solid or liquid particles suspended in air.  The air we breathe is full of these aerosol particles.  There are thousands of types of aerosol in air, coming from both natural and man-made sources.  Examples might be tiny dust particles, sand, sea salt, bacteria, tree and plant emissions, car exhaust fumes to name but a few.

Aerosols are very difficult to study and understand because there are so many types of aerosols in the air, and they are constantly changing over time.  Despite the challenges, there is a lot of research being done on atmospheric aerosols because they are very important factors in climate change and our health.  But, back to rain and snow…

It isn’t just temperature that dictates whether clouds form as snow or rain.  Specific seed particles are good for making one or the other.  Dust particles from deserts for example, are known to be very good at nucleating ice (making snow).  Experiments in laboratories can be used to mimic the conditions leading to cloud formation and this is how a lot is learned about the snow or rain forming potential of different aerosols.  But, there are also plenty of field experiments where rain or snow is collected – on the ground or by flying aircraft through the clouds and collecting samples – and the non-water components analyzed to determine what the seeds were.

A good example is the CalWater field campaign which studied aerosol impacts on clouds and precipitation over the course of 3 consecutive winters In the Sierra Nevada.  They found that during all major storms desert dust and biological residues were the most common seed particles.  Using a variety of techniques including chemistry experiments on the ground, satellite data tracking the aerosols, measurements from aircraft in the clouds and detailed weather tracking the scientists were able to trace the dust and biological aerosols leading to increased snowfall to deserts in the Middle East, the Sahara in Africa and even as far afield as China*.  It’s amazing to think that dust storms in Asia can affect the weather thousands of miles away.  I wonder who we can blame for all the rain in Wales?

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Photos courtesy of Katy Jenkins of Glynhir Mansion (Proof that it doesn’t just rain in Wales)

For more info on CalWater see:

http://www.esrl.noaa.gov/psd/calwater/overview/calwater1.html

*Science 339, 1572, 2013