< p >地球的内核是固体,因为尽管这个地区的巨大的温度,也有巨大的压力,进而提高铁和镍的熔点值超过地球的核心温度。< / p > < p >现在我们从固体内核,温度下降,压力也减少。显然因为核心固体但外核是液体,我们必须得出温度和压力降低的下降必须低于16度/绩点的梯度如下图所示(< a href = " http://www.agu.org/books/gd/v031/GD031p0083/GD031p0083.pdf " > < / >链接来源),鉴于在外地核的温度已经超过铁的熔点/镍,这是压力的函数。< / p > < p >换句话说,压力必须下降非常显著下降相比从核心温度随着半径的增加。< / p > So how is it that pressure drops off fast enough relative to temperature to give rise to the liquid outer-core. A good answer will explain how temperature drops off with radius and how pressure drops off with radius and how these compare to give rise to the liquid outer-core.