Convection is the most common type of fluid movement in nature, in technology, and even in everyday life. His research dates back just over a century, and during this time they acquired a solid basis, which we will try to present here. Thousands of articles and dozens of books are devoted to the description of convection, but the physical side of the process is rarely given enough attention. This will be done using the methods of mathematical physics, similarity and dimension theory, and connections with the scale of the theory of random motions of A. N. Kolmogorov 1934 and their development in the works of his students will be traced. They will also be brief on the main manifestations of convection in nature are discussed: movements from instantaneous and constant heat sources, convection in a rotating fluid, deep convection in the ocean, in the earth's mantle, etc. Many of these aspects are presented in the book G12 and are found in the previous paragraphs of this book. Quite systematic the presentation of the subject seems useful, but there are clarifications and their further development.