Despite the fundamental role of clouds in weather, there is much we don’t know about them. NASA intends to do something about that under a 24-month, satellite-based mission scheduled to launch next year. Called CloudSat, the program is aimed at better understanding how clouds affect climate in terms of their thickness, height, absorption, and water and ice content. NASA hopes that better knowledge of cloud properties from the top of Earth’s atmosphere to its surface will help improve the accuracy of weather forecasts.