On behalf of the International Radiation Commission (IRC) of the International Association of Meteorology and Atmospheric Sciences (IAMAS) and the Organizing Committee, we cordially invite you to attend the next quadrennial International Radiation Symposium (IRS), which will be held in Thessaloniki (Greece). IRS 2022 will provide a comprehensive international forum for presenting and discussing recent research achievements and technological developments on atmospheric radiation and related topics covering a wide spectrum of topics. Internationally recognized senior scientists, young scientists, and students will have a unique opportunity to discuss hot scientific issues, exchange new ideas and establish far-reaching collaborations. Furthermore, companies involved in radiation instruments will have the opportunity to present their latest technological achievements and disseminate in over 400 participants their applications and products.