On the mean meridional circulations in the Northern Hemisphere during the winter season



A new attempt is made to determine the mean meridional wind components of the Northern Hemisphere at different levels for the winter season December-February, and to compute the mean mass circulation as a function of latitude. The computation shows the existence of a strong ‘direct’ Hadley circulation in low latitudes and a much weaker ‘indirect’ circulation in higher latitudes. From the mass circulation in low latitudes the meridional flux of water vapour is computed, and from the divergence of this flux the difference between precipitation and evaporation from the earth's surface is evaluated for different latitudinal belts between the Equator and 40°N.