Physical Meanings of "Cave Channel" in Strong Convective Storm with Its Application

Since the "cave channel"(CC) or "zero region"(ZR) structure is suggested, several papers are published on this title. The understanding of the physical meanings of CC or ZR is deepened by these papers, but in principle and application there are questions to answer or clear up, such as the conditions of formation of CC or ZR in strong storm, the analogous CC in rain-storm, why previous studies do not indicate the existence of CC, how to find CC structure in practical application etc. These questions are answered and the meanings are further understood by observation facts and numerical simulations. It is shown explicitly as the following. The CC or ZR structure is the results of the interaction between cloud's macro-flow field and cloud's micro-particle terminal velocities in nature. Some special structure of radar echo is BWER (bounded weak echo region), WER (weak echo region) or OE (overhang echo), it is the product of the interaction too. The interaction can play very important role only when the terminal velocity of particles is equivalent to the velocity of airflow. If the terminal velocity of particles relatively is too small or too large the effects of this interaction are very weak. The study of this interaction can deepen the understanding of the dynamical and physical meanings of the radar products, it is much necessary to find the characteristic criteria for now-casting of high-impact weather and in weather modification.