Satellite Imagery Characteristics for Extratropical Cyclones and Meiyu Fronts

This paper introduced satellite imagery appearance for extratropical cyclones and Meiyu fronts. Extratropical cyclone is consisted of three conveyor belts: warm conveyor belt,cold conveyor belt and dry slot. Meiyu frontal cyclones are the ones among series cyclones at the lowest latitudes. In Eastern China due to dynamical and thermo-dynamical processes associated with specific topographical and geographical features,in the upper troposphere, there is an anti-cyclonic ridge extending eastward from Tibetan Plateau. Between this ridge and a subtropical jet stream closely to its northern side, the upper tropospheric flows diverse towards multi directions to the eastern and southern sides. Coupled with the upper ridge in the lower troposphere, there is an shear line east-west oriented with extreme wet humidity. Such three dimensional structure of the atmosphere approaches the condition of the symmetric instability. As a result, the Meiyu frontal cloud belts become dense, continuous and long lasting. It is due to the latent heating along the rain belt in the upper troposphere, after a time period about 10—15 days, the pattern is evolved, either the rain belt moves northward, or the pattern turns into longitudinal. With longitudinal pattern, the densities of the clouds vary in different regions of the cloud belt related with the vorticity and convergence in the low level air flow and its interaction with the surrounding tropical disturbances.