Hello, it is very simple

FORMATION OF RAIN WATER
TRUE CHEMICAL REACTION IN ATMOSPHERE

1-PHOTOLYSIS: (photodissociation or photo-decomposition) of ocean waters consists of the decomposition of the water molecule into molecules of hydrogen (H2) and into atoms (O) under the effect of solar radiation, The ultraviolet. In view of the abundance of H2 molecules and free O atoms, a small number of them collide and form water molecules, called water vapor In the gaseous state even if it is always a compound compound H2O)
https://en.wikipedia.org/wiki/Photolysis www.google.dz/search?q=photolysis

2-THIS WATER VAPOR H2O is in turn decomposed into H2 and O since it has got even closer to UV rays with short wavelengths (very energetic). The lighter molecules H2 will rise the most (this is called positive cloud wrongly because it is not a cloud, the cloud is formed of water molecules) and the heavier O atoms (The so-called negative cloud, the cloud is formed by molecules of water), this is what is called sublimation, the two simple gaseous bodies are free (Final state).

3-THE RISING CURRENTS of hot air represent a mechanical force opposed to that of the descending air currents, there is the opposition of two mechanical forces from which compression and under the effect of agitation and Friction as well as solar radiation, hydrogen ionizes positively and oxygen negatively and at the favorable rate of compression, the two gases combine in an explosive chemical reaction (the synthesis of water is explosive), they form the water.
Which says explosion said electric spark, detonation therefore (lightning + thunder + water = one and only operation).
The light of light comes first (speed of light 299.792.458 m / s), the sound of the explosion which is thunder (speed of sound 340 m / s) second
It occurs around the earth between 2000 to 5000 storms per second (that is to say between 172.800.000 times to 432.000.000 times in 24 H)
http://www.planetoscope.com/atmosphere/252-nombre-d-orages-dans-le-monde.html
And each storm cell can produce more than 100 flashes per minute (ie between 17,200,800,000 and 43,200,000,000 flashes) and as each flash is the index of a chemical synthesis reaction of water (H2 + O -> H2O), you can imagine the volume of water that can form in our atmosphere every second.
http://www.astrosurf.com/luxorion/meteo-orages3-eclairs.htm

4-CONDENSATION: Once the water formed as I have detailed, it suffices that a certain number of molecules of water can be united by coalescence and acquire a weight that can be influenced by the earth's attraction to fall into the form of Water droplets (rain).

The "evaporation-condensation-rain" theory is dwarfed and disabled