The shape of clouds
Climatologists’ verdict is by now definite and unanimous: the atmosphere of our planet is warming, due to the ever-increasing emission of greenhouse gases by human activity. The concentration of carbon dioxide in the atmosphere reached levels never seen in the lasts eight hundred thousand years. In order to condition international emission policies and to safeguard our planet, the ability of scientist to provide climate forecast more and more accurate and reliable is fundamental. More than a half of the uncertainty in current climate models is due to a single factor: clouds.
Their complexity and diversity has not yet been completely captured into the models used to predict the evolution of the atmosphere. The challenge is taking into account, in computer-based simulations, all the processes involved in the formation and the dynamics of clouds simultaneously. In fact, while cloud systems can extend up to thousand of kilometers, their fundamental components (water droplets and ice crystals) have sizes of less than a millimeter. Even if we understand all the involved physical phenomena, from the large-scale dynamics of cyclones to the microscopic processes concerning water phase transitions, we do not have computer enough powerful to simulate all this stuffs at the same time.
So, while waiting for technological improvements, climatologists use alternative methods in order to consider the effect of clouds on climate. Instead of calculating their properties in great detail, they deduce their mean properties from other atmospheric quantities, like temperature and humidity. The calibration and the continuous development of these techniques will be fundamental in order to obtain more and more trustworthy future climate scenarios. In this way, science can help society showing the right path to reach climate goals. As a young PhD student, I want to contribute in meeting this challenge.
