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风从哪里来?

(根据维基百科)大规模气体的流动。
风在地球表面,包括大量的空气流动。

什么力量会导致这样的群众运动的空气?

回答

风是由压力引起的差异。想到一个气球充满了空气;戳一个洞,空气就出来了。为什么?因为气球的压力比外面高,所以重新获得相等的压力,大规模举措,是风。这有更多的大气中由于地球自转和附近的表面摩擦中也扮演了重要的角色。运动navier - stokes方程,在笛卡儿空间向量形式:$ $ \ dfrac{\部分\ mathbf u}{\部分t} = - u \ cdot \ \ mathbf微分算符\ mathbf u - \ dfrac{1}{\ρ}\微分算符p 2ω\ mathbf \ \ * \ mathbf u + \ mathbf g + \ mathbf F $ $这个方程,\ mathbf u向量风美元,美元(\ mathbf u \ cdot \微分算符)美元是平流运营商\ρ是密度,美元\ mathbf \ω美元是向量的旋转地球\ mathbf g是有效重力和美元\ mathbf F是美元摩擦。lh是风的时间变化率在空间中的一个点(相对于包裹后)。园艺学会代表很多因素产生风的变化。从左到右:动量平流(非线性)——压力梯度力(这是风从高到低压力),科里奥利力(这风在北半球向右和左SH,使风流等压线平行)——重力(提供流体静力平衡PGF在垂直)——摩擦(边界层你可能认为这是美元\ν\微分算符^ 2 \ mathbf u $)对大尺度天气流在水面上,这通常被简化为一个平衡的流动称为* *地转平衡。 This a steady flow with a balance between the PGF and Coriolis force in the horizontal and hydrostatic balance in the vertical. $$ \dfrac{1}{\rho}\nabla p = 2 \mathbf \Omega \times \mathbf u $$ Which can also be written as $$u_g = -\dfrac{1}{\rho f}\dfrac{\partial p}{\partial y}$$ $$v_g = \dfrac{1}{\rho f}\dfrac{\partial p}{\partial x}$$ $$\dfrac{\partial p}{\partial z} = -\rho g$$ In these equations, $u_g$ is the geostrophic wind in the east/west direction and $v_g$ is the geostrophic wind in the north/south direction and $f$ is the Coriolis parameter ($f = 2\Omega\sin\phi$, where $\phi$ is lattitude). For this idealized geostrophic and hydrostatic balance, there is no vertical motion and all horizontal flow is parallel to isobars, flowing clockwise (counter-clockwise) around high pressure in the NH (SH) and flowing counter-clockwise (clockwise) around low pressure in the NH (SH). For curved flow, we can consider another balance, the *gradient wind balance* that allows acceleration of the flow though centrifugal forces. This can be written as (where $n$ is in the cross-wind direction): $$ \dfrac{V^2}{R_t} = -fV - \dfrac{1}{\rho}\dfrac{\partial p}{\partial n} $$ Where $R_t$ is the radius of curvature in the flow. In the limit of $R_t \rightarrow \infty$ the acceleration term vanishes and this becomes geostrophic flow. The consequence of this balance is that wind will flow slower than geostrophic balance around a low pressure center, this is said to be *subgeostrophic*. Around a high pressure center we have *supergeostrophic* flow, or faster than geostrophic. *** You may have noticed the wind balances above are non-divergent and lack vertical flow. This makes for boring weather, and does not hold near the ground or where vertical motion is large. We term the deviation from geostrophic flow the *ageostrophic* wind and this accounts for friction. This results in wind converging toward low pressure and diverging from high pressure. *** Another flow is the *isallobaric* wind, and this is wind that blows from pressure rises toward pressure falls. A place you will normally see this wind is just as a cold front passes and the pressure rises behind the front and falls in front of it. This enhances the cross frontal wind and helps produce the often strong, gusty winds after a cold front passes.

编辑总结

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\ begingroup美元我觉得任何“为什么风吹”解释至少应该提到太阳能加热,压力差异的主要原因。 \ endgroup美元
- - - - - -f.thorpe ♦
2015年5月4日19:14
2

\ begingroup美元我觉得大部分的(否则优秀)的回答是回答“如何风的运动可以描述数学”而不是“风是从哪里来的?”。 \ endgroup美元
- - - - - -半日西蒙
7月17日12:56

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