用来计算空气的折射率和色散值，在某些精细测量和校准应用下，空气的微小色散值不能忽略，对光脉冲等的传输造成影响。(In general, the dispersion of air is approximately zero, whose dispersion can't be ignored under special circumstances. The code is utilized to calculate　the refractive index of air and the dispersion.)