Since the advent of agriculture, when food supplies waxed or waned depending on the weather, human civilizations have wanted to control the weather. Ancient civilizations typically did this by praying to gods or to one God to bring rain and prosperity. In the twentieth century, however, science finally seemed to offer hope that our understanding of chemistry and meteorology could be used to affect the weather. There was considerable hope that cloud seeding, discovered in 1946, could make droughts a thing of the past. The potential of this technique never met expectations, though it still can be used under the right conditions; seeding techniques are also employed to reduce the size of hail stones so they will cause less damage. The Weather Modification Association, which was established in 1950, is still active today and supports research in this area.