<P> The Marangoni effect is the convection of fluid along an interface between dissimilar substances because of variations in surface tension . Surface tension can vary because of inhomogeneous composition of the substances or the temperature - dependence of surface tension forces . In the latter case the effect is known as thermo - capillary convection . </P> <P> A well - known phenomenon exhibiting this type of convection is the "tears of wine". </P> <P> The Weissenberg effect is a phenomenon that occurs when a spinning rod is placed into a solution of liquid polymer . Entanglements cause the polymer chains to be drawn towards the rod instead of being thrown outward as would happen with an ordinary fluid (i.e., water). </P> <P> In a zero - gravity environment, there can be no buoyancy forces, and thus no natural (free) convection possible, so flames in many circumstances without gravity smother in their own waste gases . However, flames may be maintained with any type of forced convection (breeze); or (in high oxygen environments in "still" gas environments) entirely from the minimal forced convection that occurs as heat - induced expansion (not buoyancy) of gases allows for ventilation of the flame, as waste gases move outward and cool, and fresh high - oxygen gas moves in to take up the low pressure zones created when flame - exhaust water condenses . </P>

The convection current produced due to warm sea and cold earth is called