Their model begins with clouds forming on the edges (the walls) of the open cells as seawater evaporates and rises. Eventually, the water turns to rain, which then generates the opposite dynamic of that which created the clouds in the first place. In the first stages of the cloud formation, the energy that is released as the rising vapor condenses enhances and amplifies the updraft. Later, however, once the rain starts to fall and evaporate below the cloud base, a cooling effect takes over.
This cooling effect forces the air to sink, evaporating the parent cloud along the way. The new downdraft zone forces the air around it to be lifted, creating the next generation of clouds in a location that was previously the empty center of the parent cell.
In this way, all the cells are linked, and thus the various cells’ oscillations will be synchronized with one another. A single cell cannot act on its own: It needs the “permission” and collaboration of all the neighboring ones. Koren: “Like the sound of many hands clapping in rhythm, or the synchronized flashing of fireflies on a summer night, such communication creates a self-organized system that oscillates in a coherent way.” Though the individual cells alternately clear up and cloud over, the system as a whole persists for days at a time, leading the scientists to refer to “dynamic stability” in the cloud cover.
In his previous research
, Koren investigated the role of tiny particles called aerosols – both natural and man-made – in cloud formation and precipitation. Because aerosols affect drop size and thus rainfall, he believes that the dynamics of marine stratocumulus systems could be especially vulnerable to the changes brought about by man-made particles in the atmosphere. This, in turn, could affect how well they reflect sunlight and cool the Earth.
Dr. Ilan Koren's research is supported by the Yeda-Sela Center for Basic Research. Dr. Koren is the incumbent of the Benjamin H. Swig and Jack D. Weiler Career Development Chair in Perpetuity.