Philip Laven is Chairman of DVB (www.dvb.org) which is a not-for-profit organisation developing technical standards for digital TV. Between 1997 and 2007, he was Technical Director of the European Broadcasting Union based in Geneva. Until 1997, he worked for the BBC in various senior posts including Chief Engineer R&D and Controller of Engineering Policy, thus playing a leading role in the development of the BBC's policy on many technical developments, such as the introduction of digital audio broadcasting and digital television. In his spare time, he has published about 25 peer-reviewed papers on the physics and mathematics of light scattering (see www.philiplaven.com).
All of us have had our spirits lifted by the sight of a colourful rainbow – typically seen when the weather forecast is for “sunshine and showers”. However, alert observers can see many other examples of “atmospheric optics”, ranging from complicated halos (caused by floating ice crystals) to rainbows, coronas and glories (all of which are caused by the apparently trivial process of scattering of sunlight by spherical drops of water). This talk will be heavily illustrated by pictures, accompanied by computer simulations showing, for example, how the appearance of these effects change with the size of the water droplets. Particular attention will be paid to the coloured rings of glories - which used to be rarely seen unless you were a mountaineer, but can now be frequently seen by air passengers when the shadow of their aircraft appears on clouds below them. The primary aim of this talk will be to encourage members of the audience to look out for optical phenomena.
The meeting will be held in the Institute of Geography, University of Edinburgh, Drummond Street, EH8 9XP, starting at 6 pm, with tea and biscuits available from 5:30 pm.