The formation of fog is accompanied by a simultaneous decrease in temperature and an increase in relative humidity. If water in the atmosphere is cooled rapidly to 298 K, a degree of super-saturation is reached when water drops begin to nucleate. It has been observed that for this to happen the vapor pressure of water has to be at least 12.7 kPa. What will be the radius of a water droplet formed under super-saturation? How many water molecules will be in the droplet? Conventional wisdom says that the number of water molecules on a drop should be less than the total number. Calculate the ratio of water molecules on the surface to the number in the droplet. Comment on your result. Molecular area of water = 33.5Å2