Task: Class Definition Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes 'convection'?

A. An effect due to heat sources within a local exhaust enclosure (stack) producing convective air currents with vertical velocities proportional to the rate of heat transferred to the surrounding air and to the height of rise of the heated air.
B. In general, mass motions within a fluid resulting in transport and mixing of the properties of that fluid. the concept, along with conduction and radiation, is a principal means of energy transfer.
C. The process of transport solely by the mass motion (velocity field); also, the rate of change of the value of the advected property at a given point.
D. Convection that originates from an atmospheric layer above the boundary layer.

Answer: In general, mass motions within a fluid resulting in transport and mixing of the properties of that fluid. the concept, along with conduction and radiation, is a principal means of energy transfer.