  As 5G wireless systems and networks are now being globally commercialized and
deployed, more diversified application scenarios are emerging, quickly
reshaping our societies and paving the road to the beyond 5G (6G) era when
terahertz (THz) and unmanned aerial vehicle (UAV) communications may play
critical roles. In this paper, aerial channel models under multiple
meteorological conditions such as rain, fog and snow, have been investigated at
frequencies of interest (from 2 GHz to 900 GHz) for UAV communications.
Furthermore, the link budget and the received signal-to-noise ratio (SNR)
performance under the existing air-to-ground (A2G) channel models are studied
with antenna(s) system considered. The relationship between the 3D coverage
radius and UAV altitude under the influence of multiple weather (MW) conditions
is simulated. Numerical results show that medium rain has the most effects on
the UAV's coverage for UAV communications at millimeter wave (mmWave) bands,
while snow has the largest impacts at near THz bands. In addition, when the
frequency increases, the corresponding increase in the number of antennas can
effectively compensate for the propagation loss introduced by weather factors,
while its form factor and weight can be kept to maintain the UAV's payload.
