When we were children we were taught how clouds are formed. The story goes something like this:
Water is heated by the Sun, evaporates, and rises into the sky. When the water vapor condenses, it becomes a cloud. When enough water has accumulated, the water falls in the form of rain.
This is a true explanation and does satisfy the curiosity of children. Since the question is answered so well, many adults never ask it again. But what really happens in the formation of a cloud on the atomic level?
Have you ever wondered how millions of pounds of water can be suspended above your head?
Water is a “sticky” molecule. Physicists claim that it has a negative charge meaning that it will bond with itself and many other substances.
The simplest way of understanding the atomic reaction that occurs to make clouds is to look at a pot of boiling water. When we apply heat we flood the water with free electrons causing the bonds between the water molecules to release. The electrons, from the heat, are then stuck to the freed water molecule. The abundance of electrons, attached to the freed water molecule, moving from a greater concentration to a lesser concentration, lift the water molecule out of the pot of boiling water. The water molecule will rise until the stuck electrons break free of the water molecule (in an area with a lesser concentration of electrons). The water molecule is then suspended in space bonded to another element or molecule.
If we apply enough heat to the water, we will see bubbles forming at the bottom of the pot which rise to the surface. There are so many electrons attached to the water molecules that it becomes a gas inside of a liquid.
On a larger scale, such as an ocean, heat is supplied by the sun in the form of light. Some portion of the light wave is absorbed by the molecules in the water (not necessarily the water molecule) and the electrons are freed from the light wave. The free electrons are then bonded to the water molecule and the water molecule is freed from its’ bond with the molecules around it. Because electrons move from a greater concentration to a lesser concentration, the water molecule will go along for the ride.
There are other factors that must be taken into consideration however. The temperature differential from the water to the surrounding air is going to increase or decrease the flow of water molecules.
If you live in a climate with changing seasons, you will often notice a fog rising off of a lake on a cold autumn morning. The water is warmer than the air causing more water molecules to rise out of the lake.
Once the water molecule reaches a cooler part of the atmosphere, the extra electrons that were picked up on the surface of the earth, escape the loose connections they have to the water molecule. Consequently, the water molecule stops traveling upwards based on its’ lighter than air characteristics. It may be pushed higher into the atmosphere by the heat rising from the earth below.
As the loosely connected electrons break free of the water molecule, at colder temperatures, it now attempts to bond with other water molecules in close proximity to it. The water molecule will attract another water molecule in order to “borrow” its’ electron. As this “borrowing” continues, water vapor is formed into clouds. Each water molecule is attracted to another water molecule because of its’ lack of electrons. In essence, this interaction has created a gravity in the cloud that causes water molecules to be pulled towards each other.
If you observe clouds closely, you will often see smaller clouds being pulled toward larger clouds until the small cloud is absorbed. It is fascinating to watch the gravitational pull exerted by the water molecules as they cool.
In the following discussion, the number of electrons bonded to either a hydrogen or oxygen atom are hypothetical. Since electrons are so tiny, and move so quickly, it may be impossible to count the number of electrons surrounding an atom at any point in time and space.
In the earth’s atmosphere, oxygen exists in a gaseous form. In other words, it normally floats above the surface of the earth. Hydrogen does not exist in our atmosphere. It has long since traveled into space.
Hydrogen normally consists of 1 electron and 1 proton. Oxygen normally consists of 8 protons, 8 neutrons and 8 electrons. If we add all of the ingredients together, (2 hydrogen atoms = 2 protons and 2 electrons + 1 oxygen atom = 8 protons, 8 neutrons and 8 electrons) we have 10 protons, 10 electrons and 8 neutrons. Hydrogen does not have any neutrons to contribute.
In order to combine the oxygen and hydrogen to make water, either the hydrogen or oxygen must give up a total of two electrons so that the two single hydrogen protons can bond with the electrons in the oxygen atom. This can be done with fire or a fuel cell.
The resulting atomic composition of the water molecule is 10 protons, 8 electrons and 8 neutrons. The resultant bonding of the hydrogen and oxygen is very strong. The bonds can only be broken through electrolysis or extreme temperature (3000° C).
Oddly enough, when hydrogen and oxygen are combined into a water molecule, the melting temperature is 32° F (0° C) which is a much higher temperature than either of the atoms that make water. Hydrogen melts at -259.2° C. Oxygen melts at -218.8° C. The difference in the melting point of frozen water and the melting points of the atoms that make up water is over 400° F!
Since the hydrogen and oxygen atoms must give up two electrons in order to become a water molecule, the end result is no longer a gas in our atmosphere. It is heavier than air and becomes a liquid that normally resides on the surface of the earth.
Since we now have more protons (10) than electrons (8), the water molecule will be “sticky”. It will have a tendency to loosely bond with free electrons or to electrons in other molecules.
In order for the water molecule to rise into the air, the water molecule must obtain at least two extra electrons. If the number of electrons attached to the water molecule reaches ten (the number we started with when they were both a gas), the water molecule will rise from the earth. This is caused by the fact that electrons are heat and heat rises in a gravitational environment.
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