The most basic element of full-developed convection, including those in  the atmosphere, is often considered the so-called "thermal".  A thermal can be generated in isolation by releasing an isolated thermal  anomaly at a bottom of an experimental apparatus: a donut-shaped  vorticity ring is generated by the associated buoyancy field. The goal of this talk is to present a general formulation for analyzing  the thermal vortex ring from a point of view of the vortex dynamics. This general formulation can derive Turner's classical similarity  solution, which is derived solely based on the dimensional analysis, in a deductive manner. The extension of this description to the non-similarity regime will also be discussed.