When the density [rho] is uniform, this becomes, as before in (2) § 9

p = [rho]z + p0. (3)

Suppose the density [rho] varies as some nth power of the depth below

O, then

dp/dz = [rho] = [mu]z^n (4)

z^(n+1) [rho]z [rho] /[rho]\^1/n

p = [mu]------- = ------ = ----- ( ----- ) , (5)

n + 1 n + 1 n + 1 \[mu] /

supposing p and [rho] to vanish together.

These equations can be made to represent the state of convective

equilibrium of the atmosphere, depending on the gas-equation

p = [rho]k = R[rho][theta], (6)

where [theta] denotes the absolute temperature; and then

d[theta] d / p \ 1

R-------- = -- ( ----- ) = -------, (7)

dz dz \[rho]/ (n + 1)

so that the temperature-gradient d[theta]/dz is constant, as in

convective equilibrium in (11).

Encyclopaedia Britannica, 11th Edition, "Hydromechanics" to "Ichnography" Volume 14, Slice 2 · 第 7 / 120 题