The most well-known classes of the GCR variations are: 11-year and 22-year. Although, in the shorter time scale an important class is the cosmic ray recurrence associated with the solar rotation around its axis. Because the differential rotation underlying the 27-day variation of galactic cosmic rays intensity and the functioning of the solar dynamo are inextricably linked, thus discovering new properties of this variability can contribute to the deepening of our knowledge about the dynamo nature. These studies allow not only to better understand the properties of galactic cosmic rays, but also to discover the properties of the heliosphere and Sun, about which we learn at various time scales indirectly. They can also serve in space weather research.