Notation: liquid phase property
vapor phase property
where is the radius of the drop
. assuming ideal gas behaviour
where is the equilibrium vapor pressure for flat surface.
As decreases, the equilibrium vapor pressure becomes larger than . This implies that in order to be in equilibrium with the liquid phase the vapor phase has to be super-saturated.
liquid phase property
vapor phase property
where 
is the radius of the drop
. assuming ideal gas behaviour
is the equilibrium vapor pressure for flat surface.
decreases, the equilibrium vapor pressure 
becomes larger than 
