What speed, relative to the surface, will a piece of atmosphere gain by the Coriolis effect in travelling on Venus from the equator to 30° N? In which direction will the wind produced by this effect at the top of the Hadley cell be? (Take the surface speed of the rotating planet at its equator to be 0.997 /243 that of the Earth, as the two planets are of similar size and Venus rotates once every 243 Earth days in the retrograde direction, east to west.) The Earth’s sidereal (with respect to the stars rather than the Sun) rotation period is 0.997 days.