Study of Ardmore, Oklahoma, storm clouds. I. Convective storm cloud initiation and development based on the remote sensing gravity-wave-induced convection

Convective instability can be induced by unstable vertical temperature profiles and can be supported by the release of latent heat of water vapour provided by a large quantity of moisture in the air. It can also be released by the presence of gravity waves. Large amplitude gravity waves have been linked to the onset of convective storm systems. In this study, the vertical velocity of convection initiated by gravity waves was investigated. The study of Ardmore, Oklahoma, storms showed that weak convection was initiated by gravity waves having wave periods of 35 min and the convection was enhanced by gravity waves having wave periods of 20 min. Evidence for cloud formation, due to the condensation of water vapour through convection initiated by the gravity waves, was obtained from rapid-scan satellite imagery and radar summaries. In this particular case, the convective motion, initiated and supported by the gravity-wave-induced activity (excluding contributions made by other mechanisms), reached its maximum value about one hour before the production of the funnel clouds. In this study, we did not rule out the contributions made by other mechanisms, such as low-level convergence and others, toward the initiation of convection; however, our main purpose is to discuss the role of gravity waves in wave-induced convection contributing to the fractions of formation and development of severe convective storms.