The alternation of weather in early winter in the Far East was researched from various points of view.
1) The weather in the season was considered to be due to a flow of cold Siberian air-mass and it was remarked that the weather of Japan depends on the nature of Siberian air-mass. For example, if the temperature of Siberian air-mass becomes cold, the temperature of Japan also becomes cold though there is a small time lag, say a day. The velocity of the flow was estimated from the time lag to be about 35km per hour. This agrees approximately with the velocity of cyclone and the mean velocity of monsoon.
2) Japan lies on the frontal zone between Siberian air-mass and Ogasawara air-mass, and it was shown that the path of depressions lies on a band which coincides with the frontal zone. Next, the weather was classified into two types; one is the so-called “west high and east low”, the standard type in winter, and the other is the cold front type which runs from SSW to NNE. Such a front was investigated and it was found that, on an average, the temperature difference is 3.7°C, the inclination of the front 1/130 and the velocity 43km per hour.
3) The climate in the season was considered as a diffusing process of Siberian air-mass and the diffusion coefficient was calculated from the distributions of vapour tension and temperature. The obtained value was about 5×10
9cm
2/sec.
4) The flow of energy across the frontal zone was calculated and it was found to be about 2.6×10cal/min/cm. Next, it was shown that, if there was no such flow of energy, the temperature of Siberia would become cold much faster, probably about 2 times faster than the actual. Next, the dissipation of kinetic energy of monsoon was estimated to be about 10
3erg/sec/cm
2. And considering the monsoon a heat engine, its efficiency was calculated to be about 8%.
5) One of the typical weathers in the season is the outbreak of high accompanied by cold spell. Considering that such an outbreak was the outflow of cold air accumulated over the continent of Asia, the equation which gives the change of pressure was calculated. The equation is
where Δ
p is anomaly of pressure, Δ
T temperature difference between lower and upper layers,
h height of the lower cold air,
v kinematic eddy viscosity,
g acceleration of gravity,
l Coriolian factor and α the angle between surface wind and gradient wind. This equation is the so-called diffusion equation and it was shown that the outbreak of high can be explained approximately by such an equation, through putting the coefficient to be about 10
10cm
2/sec.
6) Lastly, the 7 days' periodicity of the weather was discussed and it was attributed to the oscillation of cold air over the continent of Asia. Solving the equation derived from such an assumption, the period was calculated to be about 7.5 days, which was quite in accord with the 7 days' periodicity.
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