The existence and radiative properties of clouds can have a significant effect on the weather and a more accurate understanding is essential for improving predictions of both the weather and climate change. The most significant uncertainty is from aerosol cloud interactions. Certain pollutants in the atmosphere, such as sea salt and soot, are referred to as aerosols and act as "cloud condensation nuclei" (CCN) onto which water condenses to form cloud droplets. Their concentrations in the atmosphere therefore have a huge impact on cloud formation. To complicate matters further there exist secondary organic aerosols which are comprised of semi-volatile organic compounds. These have the ability to evaporate and condense on and off the CCN to change the properties of the aerosol particles. This process is poorly understood. While accurate models for these processes are important, the inclusion into large scale weather models necessitates fast methods of solution as the problem must be solved many times each day. As such, several so-called parameterisations have been proposed which aim to approximate the solution, often with varying success.