地球大气纬向风系、副热带高压和太阳较差自转的形成机制

利用N S(Navier Stokes)方程和一个基本假设推导出星体大气平均纬向风和平均气压公式，根据公式讨论了地球大气纬向风系和平均气压以及副热带高压的成因并进行了数值模拟。结果发现，地球大气纬向风是大气微团密度与基准大气密度存在差异而形成的，大气微团的密度大于（小于）基准密度，则为西风（东风）；密度的差距越大，风速越强。在中高纬度地区大气微团吸收的太阳辐射少而向空间辐射多，导致其密度变大，因此在中高纬度盛行西风；而在低纬度地区，因为吸收的太阳辐射多使大气微团密度变小而盛行东风。夏季（冬季）太阳辐射增强（减弱）使得大气微团密度变小（增大），进而导致中高纬度地区西风减弱（增强）和低纬度地区的东风加强（减弱）。风速的大小还与纬度的余弦成正比，这就使得最大西风带位于中纬度地区而不是大气微团密度最大的极地附近；也使得最大的东风不是发生在太阳直射点附近而是靠近赤道一侧。根据气压公式和大气密度的经向差异可以得出中高纬度区域气压随纬度的升高而减小的分布特征，而太阳辐射所造成低纬地区密度的减小是该区域气压大于中高纬度的主要原因；在赤道上纬度的正弦为零，使得气压在赤道上存在极小值，导致了赤道槽和副热带高压的形成，且太阳辐射越强、副热带高压越强。因为纬度正弦因子的存在，使得副高脊线总是位于太阳直射点的向极一侧。在假定太阳大气为理想气体的情况下，由N S方程推导出太阳大气自转角速度随纬度的变化公式，由此解释了太阳较差自转的成因在于低纬地区的大气微团密度大于高纬度，并且在赤道上大气微团的密度最大。该公式与观测得到的经验公式在略去高阶小项后一致。由此认为，太阳大气的运动在形成机制上与地球大气没有区别，不同的是在太阳表面没有象地球表面那样受太阳辐射的影响，N S方程是所有星体（包括恒星、行星）大气共同遵守的动力方程。

Formation Mechanism of Earth Atmospheric Zonal Winds,Subtropical High and Solar Differential Rotation

By using the N S equation and a basic hypothesis, the stellar atmospheric mean zonal wind and mean pressure formulas are derived. Based on these equations, the causes of earth atmospheric zonal wind system, mean pressure and subtropical high are discussed and numerically simulated. The results show that earth atmospheric zonal wind is formed by the density difference between atmospheric microcells and benchmark atmosphere. When the density of atmospheric microcells is greater (less) than benchmark atmospheric density, the direction of wind is westerly (easterly); the greater the density difference is, the stronger the wind will be. In middle and high latitude regions, the solar radiation absorbed by atmospheric microcell is less than their radiation into the space, which makes the density increase, so the west wind prevails in middle and high latitude regions; in the low latitude region, east wind prevails because the solar radiation absorbed by atmospheric microcell is more than their radiation. In summer (winter), the solar radiation strengthens (weakens), which makes the density of atmospheric microcells increase (decrease) and leads to the west wind in middle and high latitude areas weakening (strengthening) and east wind in the low latitude areas strengthening (weakening). The wind speed is proportional to cosine of latitude, which makes the strongest westerly belt located in the middle latitude region but not polar region where the density of atmospheric microcells is the biggest, and it also makes the strongest east wind appears not around the direct sunlight point but near the equator side. According to the pressure formula and the meridional difference of atmospheric density, the distribution feature that the pressure decreases as latitude increases in the middle and high latitude regions can be gained. The decreasing of density caused by solar radiation in the low latitude region is the main reason to make the pressure higher in this region than in middle and high latitude areas. The sine of latitude on equator is zero, so there exists a minimum of pressure on the equator, which leads to the formation of the equatorial trough and subtropical high, and the stronger the solar radiation is, the stronger the subtropical high will be. Because of the existence of latitude sine factor, the axis of ridge is always on the polar side of the direct sunlight point. Based on assumption that the solar atmosphere is ideal gas, the formula of the solar atmospheric rotation angular velocity with latitude is derived by using the N S equation, which explains the cause of the solar differential rotation; that is, the micelle density at low latitudes is larger than that at high latitudes and it is largest at the equator. The formula is fully consistent with the empirical formula by observation in omitted higher order small items. These results indicate that the movement of the solar atmosphere has no difference with the earth atmosphere in formation mechanisms; the difference is that there is no solar radiation on the surface of the sun as the earth surface; the N S equation is suitable for all stars.