Abstract. Temperature and velocity fields near an air-bubble in silicon-oil under a heated horizontal wall were investigated. The T* studies were made with silicon oils of different viscosities so that a t wide range of Marangoni numbers was encountered. Schlieren interferograms were taken to analyse the temperature field. For the u axisymmetric problem the Abel integral equation was solved numerically by using a coefficient procedure. From the recorded temx perature distributions isotherms, radial temperature lines and the y temperature along the bubble surface were determined graphically, z At low Prandtl-and high Marangoni-numbers an oscillatory instaz~ bility was observed. The flow field was investigated with neutralz* buoyant light scattering glass spheres by observation of the meridian plane of the bubble with a thin light-sheet. The convective mechanism of the flow was recorded photographically by taking pictures with various exposure times. Thus a qualitative and quantitative description of the flow was possible.

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