Venus's General Circulation is a Merry-Go-Round

Abstract

It is suggested that the atmosphere of Venus might rotate even if the planet did not, due to an apparently new nonlinear instability. One expects convention due to solar heating; if somehow a vertical shear of the horizontal wind arises, its advection will tilt the cells. The tilt of the cells will cause a correlation between the vertical and horizontal velocities, i.e., a Reynolds stress, of the correct sign to reinforce the original shear. Since the time derivative of the mean shear is proportional to the tilt, and the tilt is proportional to the shear for small shear, the mean shear will grow exponentially if the damping is not too heavy. The important requirement is that the cells to be tilted have their own energy source. The range of parameters for which this mechanism is found to work numerically includes those estimated for the atmosphere of Venus.