Two intese magnetic clouds interacted with same corotating high-speed solar wind stream recurring in two successive rotations during the fall of 1978. For the August 27, 1978 event, an intense magnetic cloud was overtaken by a corotating high speed stream, the first half of the cloud can be identified with the cloud body that still retains the basic properties of a simple intense cloud; while the second half is the interaction region resulted from the overtaking magnetic cloud by the high speed stream, the speed profile of which displays a two-steps feature. For the September 25, event, another extraordinary intense magnetic cloud was overtaking the corotating high speed stream recurring again, the first half of the cloud can be identified with an interaction region; while the second half is the cloud body itself with a rather complex structure than the simple cloud without interactions. In the second case, the bulk velocity reached a very high peak value greater than 900km/s in the interaction region, also the Alvenic speed a very high value above 600 km/s in the cloud body which was very close to the local solar wind speed. These two events discussed in this paper show further the important role played by an enhancement of the Alfvenic speed in accelerating the magnetic cloud. The properties of the geomagnetic storm and the cosmic ray decrease caused by the clouds are also briefly discussed in association with the Kp category of geomagnetic storm proposed by he author.
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