From the Tropics to the Poles in Forty Days

Field experiments show that the poleward velocity of high-altitude weather balloons may, on rare occasions, be much higher than the observed poleward winds, while their eastward velocity is much slower than the observed eastward winds. Considering a simple physical model of horizontal particle’s motion in the atmosphere, which includes a realistic model of the pressure field, it is shown that the existence of a nearly flat parabolic resonance in the model gives rise to such flights of balloons on the observed timescales even though the associated atmospheric pressure field does not support large poleward velocities. *Department of Applied Mathematics and Computer Science, Weizmann Institute of Science, Rehovot, Israel. Department of Atmospheric Sciences, Hebrew University of Jerusalem, Jerusalem, Israel. Corresponding author address: Dr. Vered Rom-Kedar, Department of Applied Mathematics and Computer Science, Weizmann Institute of Science, P.O.B. 26, Rehovot 76100, Israel. E-mail: [email protected] In final form 7 August 1997. ©1997 American Meteorological Society