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科里奥利效应形成的必要条件,但不是为了维护一个热带气旋。一旦形成,在一个成熟的热带气旋强度飓风风平衡旋转,压力梯度和离心力,科里奥利效应相比可以忽略不计。特别是如果热带气旋很小但激烈。这样一个成熟的热带气旋强度飓风不会遇到困难如果越过赤道。其循环将归类为气压前穿越赤道,后来反压。这样一个成熟的热带气旋强度飓风不会削弱跨越赤道后由于逆转科里奥利效应(虽然它可能会削弱或加强由于其他原因)。一个反压旋风完全符合运动定律。除了最小的尺度,如尘暴或漩涡很难启动,但一旦启动就可以稳定。跨越赤道热带气旋可能只有这样,天气尺度可以发起反压旋风。如果一个热带气旋,尤其是一个大,横跨赤道,达到明显的纬度相反的半球,说外热带或更低的中纬度地区,然后梯度风近似而不是旋转风近似适用。 But antibaric gradient wind is still a stable flow. See for example James R. Holton and Gregory J. Hakim, Dynamic Meteorology Fifth Edition Section 3.2.5 on pp. 74-77. In baric gradient flow the Coriolis and centrifugal forces acting outwards balance the pressure-gradient force acting inwards. In antibaric flow the centrifugal force acting outwards balances the pressure gradient and Coriolis forces acting inwards. Thus for a given pressure gradient and radius of curvature of the isobars, the centrifugal force must be stronger, and hence the wind speed higher, for an antibaric tropical cyclone than for a baric one. This does not mean that a tropical cyclone must intensify if it crosses the equator. Whether baric or anitbaric, its intensity is determined by the available energy or exergy corresponding to the sea-surface and tropopause temperatures (with possible deductions for wind shear, entrainment of dry air, land interaction, etc.) The First and Second Laws of Thermodynamics require that the pressure gradient and radius of curvature of the isobars must adjust to the exergy supply --- not vice versa. According to Holton and Hakim, an antibaric (synoptic-scale) hurricane can easily exist if it is centered say only a few degrees from the Equator in the opposite hemisphere, but this becomes more and more difficult and hence more and more unlikely with increasing latitude in the opposite hemisphere. Whether at some latitude in the opposite hemisphere it becomes absolutely impossible seems to be an open question. Small-scale antibaric cyclones (dust devils, whirlpools, waterspouts, and to a lesser extent tornadoes) can easily exist at any any latitude where sufficient exergy exists to generate and maintain them.