Scientific Rationale:Nearly all of the quantitative information we have about the cosmos is the result of spectroscopy, the science of using spectra to make physical measurements. The spectrum forms in highly non-equilibrium gas and dust. Analytic theory cannot be used to understand the conditions so numerical simulations are required. Cloudy is a code that does this - it calculates the ionization, chemistry, radiation transport, and dynamics simultaneously and self consistently, building from a foundation of atomic and molecular processes. The result is a prediction of the conditions in the material and its observed spectrum.

Cloudy is used today to study a variety of problems at many wavebands e.g., radio, IR, optical, UV, X-ray where molecular/atomic signatures are important. SDU, Weihai, is organizing a workshop to train young researchers especially Ph. D. Students and postdocs on simulating photoionised plasmas with Cloudy. Workshop format:The workshop will cover observation, theory, and apply Cloudy to a wide variety of astronomical environments, including the interstellar medium, AGB stars, Active Galactic Nuclei, Starburst galaxies, and the intergalactic medium. The lectures and hands-on sessions will be carried out by Gary Ferland. The sessions will consist of a mix of textbook study, using Osterbrock & Ferland, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, and application of Cloudy. Participants will break up into small teams and organize research projects of mutual interest.