Some methods for the numerical prediction of the velocity and direction of wind were investigated and they were summerized as follows.
(1) Gradient wind is easily calcuiated by giving the pressure and temperature distribution and a nomogram to calculate the wind velocity from the pressure gradient, latitude and radius of curvature is made assuming the air density to be 1.1×10^-3gr/cm³.
(2) The relations between surface and gradient wind are functions of pressure distribution as well as latitude of the station, and the mean values of the ratio of the velocity of the surface wind to that of the gradient wind and the angle between the surface wind and the isobar are calculated for some standard pressure distribution.
(3) The diurnal variation of the wind velocity is caused by diuranal change of the stability of the lower layer due to solar radiation and following similitude law between the air temperature and the wind velocity is proved theoretically and confirmed by the results of the observation where V₀ and _??_₀ are the velocity and the temperature in the upper layer.
(4) Diurnal change of wind velocity V, such as land and sea breaze, mountain and vallcy wind, is theoretically proved to be given by V=b √ΔT where b is a contant, ΔT the amplitude of diurnal change of air temperature.
(5) The wind velocity in the area of cyclone or typhoon is given by following empirical formula V=α√760-p where α is a constant, p pressure at the center of depression.
(6) The wind velocity at cold front is conservative at least during 12 hours, hence it is predicted by mere extrapolation of the motion of the front.