Over time, atmospheric ducts have been studied in a bid to understand and harness for optimal tropospheric propagation of radio waves. The most useful quantity in the study of ducts is the modified refractivity. The gradient of modified refractivity is used in the classification of anomalous propagation conditions. This study characterizes modified refractivity across arid regions of Nigeria, using meteorological data obtained from the European Centre for Medium – Range Weather Forecasts (ECMWF) Re-analysis 5 (ERA-5. It takes a bit - by - bit look at the variables that form radio signal trapping from the very fundamental temperature and relative humidity to the modified refractivity gradient which describes the radio signal trapping characteristics. The study location of relevance is the arid region of Nigeria, and five locations are randomly selected. The analyses of results show a high occurrence of ducts through diurnal and seasonal variations in the arid region. These results are in agreement with the physics of the meteorological parameters in which modified refractivity is dependent upon.