As far back as the 1920s, the great Russian naturalist Aleksandr Chizhevskiy pointed out the interaction between solar activity and various natural processes on Earth, including the weather. He also drew attention to the role of ions in the atmosphere and their ability to absorb moisture. Today, ionisers that purify the air can be found in many homes. The prototype for these was the so-called "Chizhevskiy chandelier", designed back in the twenties. This "chandelier" bore an outward resemblance to the lighting chandeliers that were common in those days, but instead of producing light, it emitted a stream of electrons which combined with oxygen molecules to form negatively charged oxygen ions. Scientific developments at the end of the twentieth century also shed light on one of the mechanisms of the Sun’s influence on the weather. The Russian scientists Pudovkin and Raspopov demonstrated the importance of the influence of galactic cosmic rays on the Earth’s atmosphere and the role of solar activity in modulating the flow of rays reaching the atmosphere. At times of enhanced solar activity, the stronger solar wind and magnetic field in the Earth’s magnetosphere have the effect of partially slowing and deflecting the flow of cosmic rays, while in years when the Sun is calm the flow of rays reaching the atmosphere is greater. How do cosmic rays interact with the Earth’s atmosphere? The high-energy protons, of which cosmic rays largely consist, ionise air molecules. The ions produced become centres of water vapour condensation. The molecular clusters grow by attracting increasing numbers of water molecules, as a result of which clouds form. The heavier the cloud cover, the less direct solar radiation reaches the Earth’s surface, and the less cool it is at the surface. Danish scientists have demonstrated a 95 pc correlation between the area of global cloud cover and the variation in flow of galactic cosmic rays. Of course, there can also be artificial sources of atmospheric ionisation. Chizhevskiy showed that fine metal spikes supplied with a high electrical potential can be very efficient ionisers. This idea was taken up by the Russian physicist Lev Pokhmelnykh, who created appliances that could generate ion streams over large areas.