Under the influence of solar heat water from the surface of lakes, rivers, seas, oceans and streams evaporate, turning into steam. Steam is very light, it rises up into the air, where tiny water droplets gather in clouds and clouds. Water droplets so small that they float in the air. If it becomes warmer, the cloud may completely disappear, to dissolve the droplets evaporate and become invisible. If cold, the droplets merge - hundreds of thousands of them form one full drop. These droplets become too heavy to continue soaring in the sky, they fall to the ground - rain.
The rain comes, when small droplets of water collected in the cloud, stick together and grow. If the air is no longer able to keep them, they fall to earth as rain.
The wind carries the clouds above the earth, and they shed on it the life-giving water. After all, no rain will not grow trees, flowers, grass.
We can call the "rain". Fill with ice cubes saucepan with handle and hold it over a large pot of boiling water (be careful not to aspartase!). What will happen? Very moist, hot air, saturated steam, rises and heats the walls of the ice pan. The steam that condenses, settling on the walls of the pan, degrade in large drops and trickles down. It's raining!