Light Extinction and Scattering - Dean Atkinson

Uploaded by armgov on 15.07.2010

So we basically have an experiment where we've got a couple of good mirrors
and we've got a laser, and we shine the laser towards this setup with the two mirrors
and the light bounces back and forth between those mirrors a lot of times.
And you just basically figure out how long it takes for the photons to go away.
So it's very analogous to what actually happens in the atmosphere when we're actually measuring these things.
And then we've got another measurement that measures scattering
which is when light hits a particle and bounces in another direction
which is one of the main mechanisms that leads to extinction.
And the cool thing about measuring extinction and scattering is that if you measure both of them,
you can take the difference between them and find out how much light is lost due to absorption
which is important for two reasons.
Number one, the things that do the absorbing tend to be the things that are the worst health effects:
black carbon, soot, and stuff.
And then the other thing is the warming, the black particles in the atmosphere
are actually warming the atmosphere, and so there's been a suggestion
that if you just stopped burning things in an uncontrolled manner and stopped putting so much soot in the atmosphere
you could hold off on the effects of the CO2 for maybe 10 years or something like that
giving us a little bit of time to figure out something else to do.