Subspecies. 1  H. c. charithonia, Ecuador. 2  H. c. simulator, Jamaica. 3  H. c. bassleri, Colombia. 4  H. c. churchi, Haiti. 5  H. c. tuckeri, Florida. 6  H. c. vazquezae, Mexico. 7  H. c. ramsdeni, Cuba. 8  H. c. antiquus, St. Kitts, Antigua.
See also: Convection. In the field of fluid dynamics, a convection cell is the phenomenon that occurs when density differences exist within a body of liquid or gas.These density differences result in rising and/or falling currents, which are the key characteristics of a convection cell.ee also: Convection. In the field of fluid dynamics, a convection cell is the phenomenon that occurs when density differences exist within a body of liquid or gas.
Pumice is a common product of explosive eruptions (plinian and ignimbrite-forming) and commonly forms zones in upper parts of silicic lavas. Pumice has an average porosity of 90%, and initially floats on water. Scoria differs from pumice in being denser.With larger vesicles and thicker vesicle walls, it sinks rapidly.coria is another vesicular volcanic rock that differs from pumice in having larger vesicles, thicker vesicle walls and being dark colored and denser. Pumice is created when super-heated, highly pressurized rock is violently ejected from a volcano.