On middle layer(500 hPa),the meridional movement of westly belt in high-middle latitudes strengrhen(weakened),there are +-+wave train distributions from the high latitude region to the north of Baikal to the height field near Japan.

• 多(少)雨年,中层500 hPa中高纬西风带经向运动加强(减弱),从贝加尔湖以北的高纬地区到日本附近的高度场呈+-+(-+-)的波列分布。