The lecture was filmed in April 2014 when it was given as the KIT Climate Lecture. Short abstract: In response to global concern about water shortages, cloud seeding - a form of intentional weather modification which has been used for rain enhancement for about 60 years - is receiving renewed attention. According to the WMO, there are presently over 80 cloud seeding projects around the world. An overview of existing research, however, shows that, while cloud seeding affects micro-physical processes in clouds, there is little evidence that it affects rain on the ground. The lecture will focus on the things we learned from a number of cloud seeding experiments carried out in Israel over the past fifty years. Therefore, results from experiments using silver iodide (AgI) or hydroscopic particles (e.g. sea salt) will be shown.