Figure 2.
Results of CFD calculations for balloon physical configuration and propulsion assuming 1 m s−1 at 20 km altitude. (a) The plume radius—defined by a passive tracer concentration of 5×10−3 of the initial peak concentration found on the centreline of the well-developed plume—as a function of the distance downstream (km). Plume dispersal will be dominated by wakes generated by balloon motion. The plume initially expands rapidly, slowing after a few hours towards an asymptotic radius. (b) The tracer concentration at distances of 1000 and 3000 m downstream as a function of plume radius. (c) The concentration of a passive tracer (arbitrary units) released from the balloon gondola as it travels right to left.