On the Structure of Typhoons (2nd Report)

[摘要] On the dynamical formula for the formation of eyes of Typhoons and the deflecting angle of winds in case of circular isobars.It is well known that many authors have theoretically treated the famous Manila Typhoons, which was observed at noon, Octobar 20th, 1882, and believed as providing a suitable example of the eye that is warmer and drier than the outer part as if caused by the suosiding air.We obtained some important data by an autographic recorder of temperature when the centre of a Typhoon passed the weather station at Giran Situated at the middle part of Giran plain near the Seashore at 23th, September 11th, 1942. By this data as shown in fig.2 we realized the existence of a circular surface of discontinuity on the earth's surface. Such a surface of discontinuity has already been suggested by Haurwitz, Brunt, and Bjerknes, who derived the formulae for the inclination of a circular surface of discontin_??_ty.From the results as shown in table (1), we could find the fact that the central part of Typhoonis generally of a air mass warmer than the outer part, but not so dry as that of the famous Manila Typhoon. It may therefore be suggestea that the warmer eye is causea by the Sun's radiation passing through the thin cloud layers, and the transition of the air mass from the warmer region.By this reason, we may assume that the motion of the air referred to the centre within the boundary of the eye is nearly tangential to the circular isobars, and the vertical motlon is negligible.Now we have derived a formula for the deflecting, angle of winds in the case of circular isobars, as follows; where P is pressure, ρ density, R friction, l is written for 2ω sinφ, β the angle between R and V, V is the wind velocity, ω is vertical component of the wind, ψ is the deflecting angle of the winds.We may consider that the deflecting angle ψ tends to zero at the boundary of an eye at a distance _??_0 from the centre, then we get However it is difficult to solve the equation (1) including, such unknown quantities on the right hand side as Cosβ, and W which are not easily obtained from the results of observations.Therefore we try to determine the angle ψ from the empirical formula in the following manner. and by differentiating where β is the wind direction and α is determined from the track of the Typhoon, in many cases, β is almost constant until the centre comes close to the station, Δ is the minimum distance from the tack.Furthermore, we can determine the angle ψ, when the path of the Typhoon curves.

[学科分类] 大气科学