Normally unmanned installation Normally unmanned installation A Normally Unmanned Installation (NUI) is a type of automated offshore Oil/Gas platform designed to be primarily operated remotely, without the constant presence of personnel. These generally were characterized by their small size, often consisting of just a well bay with a helipad on top. They are often a compromise of providing the convenience of surface wellheads, which are easier to build and maintain, while avoiding the high operating costs of a full production platform. They are generally only used in shallower water, where constructing many small NUIs is a relatively easy and cheap option as compared
Rear flank downdraft Rear flank downdraft The rear flank downdraft or RFD is a region of dry air wrapping around the back of a mesocyclone in a supercell thunderstorm. These areas of descending air are thought to be essential in the production of many supercellular tornadoes. Large hail within the rear flank downdraft often shows up brightly as a hook on weather radar images, producing the characteristic "hook echo", which often indicates the presence of a tornado. The rear flank downdraft can arise owing to negative buoyancy, which can be generated by cold anomalies produced at the rear of the supercell thunderstorm by