How Does a Water Drop Form?
A water drop is a small column of liquid, bounded completely or nearly by free surfaces. It may form by condensation of a vapor, or it may be the result of atomization of a larger mass of liquid. The most common example of a water drop is rain — droplets falling from the sky.
Scientists have discovered that chemical reactions occur much faster in the microdroplets of water than they do in larger bodies of water. These microdroplets are so small that they can even pass through solid barriers, such as glass or paper, but they still exhibit the same basic properties of chemistry as their larger counterparts. This discovery may help scientists understand a number of different phenomena, such as how lightning works and how antibiotics work.
The most important force that keeps a droplet secure on a surface is surface tension, which is the tendency of the water molecules to stick together. This force is strongest in the center of the droplet, where most of the water molecules are surrounded by other water molecules, and it decreases as the size of the droplet increases. If the droplet is disturbed by a stronger force, such as gravity or air resistance, it will break apart into smaller droplets.
When a droplet of water is formed, it begins to suck up water from its surroundings. This suck-up action is a function of surface tension and its ability to attract the surrounding water molecules. If a large enough quantity of water is sucked up, the force of gravity becomes greater than the force of surface tension and the droplet drops.
If a water droplet has not yet frozen, it will continue to suck up other water until its size is large enough for it to lose its surface tension. At this point the water will begin to freeze, releasing latent heat that must be used up before it can raise the temperature of the droplet above its freezing point. The rate at which the water freezes will depend on the temperature of the environment.
Many experts believe that abiotic (nonliving) processes at the interface of water microdroplets and the air helped create the first biopolymers, including amino acids. These first molecules then became the building blocks of the earliest living cells on Earth, which eventually evolved into complex multicellular organisms. Water droplets are also believed to play a role in natural weather phenomena, such as fog and rain. Water droplets are also an important vehicle for the spread of disease, such as malaria. For these reasons, medical researchers are continuing to study the behavior of water droplets as a means of improving prevention and treatment methods for disease. They are especially interested in the formation of microscopic droplets at the boundary between air and water. Various treatments can be used to change the properties of water so that it does not cause disease, and scientists are also working to develop methods to clean and disinfect these droplets.