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Geostationary satellite Feng Yun (FY-2D) has been used to observe the development of typhoon Ketsana from 21 Sep to 4 Oct 2009. Cloud changing from day to day and rainfall distribution patterns during typhoon period are observed. The relationships of the clouds and rainfall variation in 3 stages of typhoon conditions a) open sea, b) approach to the coastal line and c) landfalling are studied. At the same time, Skew-T charts are used to validate the atmospheric conditions in Vietnam for the 3 stages of the Ketsana. Mountainous in Vietnam and Cambodia are believed to affect the cloud movements and rainfall distribution patterns of Ketsana. The most distinct of the typhoon-orography effects in Indo-China occurred at Vietnam since outer circulation of Ketsana which bring along the raining clouds are deformed and rainfall distribution patterns varied as well when it approached to and passage this region by encounter mountains range of Ngoc Linh and Chu Yang Sin. Part of the low level clouds trapped by these mountains so clouds structure are deformed and heavy rainfall occurs at surrounding high terrains regions to coastal line due to the friction and blocking of the islands topography. By this remote sensing technique, not only forecasting of the tropical cyclone can be estimated but the typhoon impacts also can be defined and the disaster zones also can be determined as well.