Turbulent Solar Plume
Joey Mendoza (NCAR), Mark Rast (NCAR)

The simulation was conducted on NCAR's supercomputers. The simulation domain was 504 x 504 x 2048 grid points in dimension, and from it 500 snapshots, over 9 terabytes of data, were stored. This single frame is derived from 2 gigabytes of data and was volume rendered using a combined analysis/visualization package, VAPOR, developed at NCAR.
The outer one third of the Sun is convectively unstable. Driven by heat from nuclear fusion in the solar core and radiative heat loss (cooling) from the surface, the outer layer of the Sun boils like a pot of water. Gas near the surface cools rapidly by radiating energy (the light that we see). This radiation is not uniform over the Sun's surface, so some sites become cooler and denser than their surroundings. These denser sites become down-flowing, cold plumes as the heavier gas sinks. The downward directed plumes are similar to, but opposite of, the warm upward plumes observed from chimneys on cold days. Unlike chimney plumes, solar plumes are enormous (300km in diameter) and the gas may descend at supersonic speeds. Rather than expanding and slowing as they rise, like chimney plumes, the downward directed solar plumes are compressed and accelerated with depth. The plumes become turbulent below the solar surface due to secondary shear flow instabilities. This image depicts a computer simulation of one such plunging plume.

Traveling