  Clouds microphysics describes the formation and evolution of cloud droplets,
rain, and ice particles. It is among the most critical factors in determining
the cloud's size, lifetime, precipitation, and radiative effect. Among all
cloud types, the small clouds, characterized by weak updrafts, that are close
to the haze-to-cloud transition pose challenges in measuring them and
understanding their properties. They are superabundant but hard to capture by
satellites and often falsely regarded as aerosols. K\"ohler's theory explains
droplet activation and their growth by condensation at the earliest stages of
cloud development. It fully describes the thermodynamic state of a single drop
but falls short when explaining the collective behavior of large populations of
particles. This is especially important when the supersaturation pool is
limited. We present an analytical framework to extend K\"ohler's theory to
coexisting cloud droplets. Our results suggest hysteresis and asymmetry in the
process of droplet activation and deactivation. The turbulent nature of clouds
is incorporated into our model formulation as Brownian noise to provide
explicit droplet size distributions and activation timescales. The theoretical
findings are confronted with experimental data stemming from laboratory clouds
created in the Pi convection chamber, suggesting a new way of understanding
haze-to-cloud transitions and small cloud formation processes.
