Heating of water on the Earth surface leads to its vaporization and accumulation in the atmosphere. Water is an indispensable component of the cycle of substances in the atmosphere. Also, molecules of liquid water act as sinks of CO2. In the atmosphere, there are three kinds of water: gas (water vapor), liquid (droplets of rain) and solid water (ice or snow). In gas state molecules of water have a curved shape, and in liquid or solid states they form hydrogen bonds between atoms of hydrogen and atoms of oxygen.