An integral part of our environment in addition to the surface of the Earth is the adjacent part of the atmosphere, the lower layer of the troposphere. This part of the troposphere has essential influence on weather evolution and information on its condition is an important part of the weather forecasting models. Standard methods of the data acquisition such as radars, satellites and weather stations do not provide information with sufficiently high temporal and spatial resolution. The subject of the article is a method of monitoring the condition of lower layers of the troposphere by passive monitoring and evaluation the parameters of cellular network signals. The elementary theory of an virtual sensor for the atmospheric radio refractive index monitoring and the preliminary results of experimental monitoring of the selected meteorological situation are presented.