Roger-Maurice Bonnet*Michel Blanc Originally published in the journal Space Science Reviews, Volume 137, Nos 1-4. DOI: 10. 1007/s11214-008-9418-0 (c) Springer Science+Business Media B. V. 2008 "Planetary Atmospheric Electricity" is the rst publication of its kind in the Space Science Series of ISSI. It is the result of a new and successful joint venture between ISSI and Eu- planet. Europlanet is a network of over 110 European and U. S. laboratories deeply involved in the development of planetary sciences and support to the European planetary space exp- ration programme. In 2004, the Europlanet consortium obtained support from the European Commission to strengthen the planetary science community worldwide, and to amplify the scienti c output, impact and visibility of the European space programme, essentially the - ropean Space Agency's Horizon 2000, Cosmic Vision programmes and their successors. Its presentcontractwiththeCommissionextendsfrom2005to2008,andincludes7networking activities, including discipline-based working groups covering the main areas of planetary sciences. A new contract with the Commission, presently under negotiation, will extend - roplanet's activities into the period 2009-2012. With the broad community connection made through its Discipline Working Groups and other activities, Europlanet offers an ideal base from which to identify new elds of research for planetary sciences and to stimulate coll- orative work among its member laboratories.

Roger-Maurice Bonnet*Michel Blanc Originally published in the journal Space Science Reviews, Volume 137, Nos 1-4. DOI: 10. 1007/s11214-008-9418-0 (c) Springer Science+Business Media B. V. 2008 "Planetary Atmospheric Electricity" is the rst publication of its kind in the Space Science Series of ISSI. It is the result of a new and successful joint venture between ISSI and Eu- planet. Europlanet is a network of over 110 European and U. S. laboratories deeply involved in the development of planetary sciences and support to the European planetary space exp- ration programme. In 2004, the Europlanet consortium obtained support from the European Commission to strengthen the planetary science community worldwide, and to amplify the scienti c output, impact and visibility of the European space programme, essentially the - ropean Space Agency's Horizon 2000, Cosmic Vision programmes and their successors. Its presentcontractwiththeCommissionextendsfrom2005to2008,andincludes7networking activities, including discipline-based working groups covering the main areas of planetary sciences. A new contract with the Commission, presently under negotiation, will extend - roplanet's activities into the period 2009-2012. With the broad community connection made through its Discipline Working Groups and other activities, Europlanet offers an ideal base from which to identify new elds of research for planetary sciences and to stimulate coll- orative work among its member laboratories.

Electrical processes take place in all planetary atmospheres. There is evidence for lightning on Venus, Jupiter, Saturn, Uranus and Neptune, it is possible on Mars and Titan, and cosmic rays ionise every atmosphere, leading to charged droplets and particles. Controversy surrounds the role of atmospheric electricity in physical climate processes on Earth; here, a comparative approach is employed to review the role of electrification in the atmospheres of other planets and their moons. This book reviews the theory, and, where available, measurements, of planetary atmospheric electricity, taken to include ion production and ion-aerosol interactions. The conditions necessary for a global atmospheric electric circuit similar to Earth s, and the likelihood of meeting these conditions in other planetary atmospheres, are briefly discussed. Atmospheric electrification is more important at planets receiving little solar radiation, increasing the relative significance of electrical forces. Nucleation onto atmospheric ions has been predicted to affect the evolution and lifetime of haze layers on Titan, Neptune and Triton. For planets closer to Earth, heating from solar radiation dominates atmospheric circulations. Mars may have a global circuit analogous to the terrestrial model, but based on electrical discharges from dust storms, and Titan may have a similar global circuit, based on transfer of charged raindrops. There is an increasing need for direct measurements of planetary atmospheric electrification, in particular on Mars, to assess the risk for future unmanned and manned missions. Theoretical understanding could be increased by cross-disciplinary work to modify and update models and parameterisations initially developed for a specific atmosphere, to make them more broadly applicable to other planetary atmospheres. The possibility of electrical processes in the atmospheres of exoplanets is also discussed."